National Climate Report - August 2017
- Climate Highlights — summer (June-August)
Jun-Aug Average Temperature Departures
Jun-Aug Percent of Average Precipitation
- The national average summer (June-August) temperature for the contiguous U.S. was 72.7°F, 1.3°F above average and the 15th warmest summer in the 123-year period of record.
- Above-average temperatures spanned the western third of the country. California and Nevada were record warm, and six additional western states had temperatures among their 10 warmest. This was California's second consecutive record warm summer; its last four summers are among its five warmest.
- Nine states in the South and Midwest observed a cooler-than-average summer in 2017. This was primarily a result of cooler-than-average afternoons across these regions.
- Seventeen of the past twenty summers, including the last seven, have been warmer than average.
- The contiguous U.S. average maximum (daytime) temperature during June-August was 85.4°F, 1.0°F above the 20th century average, the 25th warmest on record. Above-average maximum temperatures were observed across the West. California had its warmest summer maximum temperature on record. Seven additional western states were also much-warmer than average. Below-average maximum temperatures were observed across many locations from the Great Plains to East Coast. Four states across the Deep South had much-below-average maximum temperatures.
- The contiguous U.S. average minimum (nighttime) temperature during June-August was 60.0°F, 1.6°F above the 20th century average, the 11th warmest on record. Above-average minimum temperatures spanned the West and Southeast with near-average conditions across the central and parts of the northeastern United States. California and Nevada each had a record warm summer minimum temperature.
- Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during summer was 38 percent above average and ranked as the 27th highest value in the 123-year period of record.
- The summer's precipitation average of 9.19 inches was 0.87 inch above average and the 16th wettest summer on record.
- Mississippi observed a record amount of summer precipitation at 20.75 inches, 7.75 inches above average. This exceeded the previous record set in 1989 by 0.41 inch. Alabama, Florida, Louisiana, and Texas also had much above average precipitation for the season.
- The Northwest, Northern Plains, parts of the Midwest, and parts of New England experienced a dry summer. Montana had its second driest summer on record, 3.20 inches below average, reflecting worsening drought conditions during the season and setting the stage for extensive wildfires.
Other Weather and Climate Indicators
- Although the nation on average was wet, drought expanded during the season, most notably in the Northern Plains, according to the U.S. Drought Monitor. Nationally, 11.8 percent of the contiguous U.S. ended the season in drought, up 6.5 percentage points since the beginning of the summer season. Montana's drought coverage ballooned from 0.0 percent to 90.2 percent during the season, with nearly one quarter of the state in the most severe classification (D4, 'Exceptional Drought'). Similarly, drought grew during summer in North Dakota from 24.1 percent coverage to 65.8 percent coverage, and in South Dakota from 20.4 percent to 68.9 percent.
- The U.S. Climate Extremes Index (USCEI) for the summer was 24 percent above average and the 16th highest value on record. On the national scale, extremes in warm maximum and minimum temperatures were much above average. The USCEI is an index that tracks extremes falling in the upper or lower 10 percent of the record. The index covers land-falling tropical cyclones, temperature, precipitation, and drought across the contiguous U.S.
- On the regional scale, the CEI was much above-average in the West and Northwest, where extremes in warm maximum and minimum temperatures were record and near-record high.
- Climate Highlights — August
August Average Temperature Departures
August Percent of Average Precipitation
- The August national temperature was near average at 72.0°F, 0.1°F below average, tying 1921 as the 53rd coolest on record.
- Although the August temperature was categorized as near-average nationally, there were stark regional differences. The western U.S. was very warm, while the central U.S. was quite cool.
- California, Oregon, and Washington each had their warmest August on record. The California statewide average temperature of 77.8°F tied with 1967 and 2012 at 4.1°F above average. Oregon's average temperature was 69.8°F, 5.9°F above average. Washington's was 68.7°F, 5.2°F above average.
- Average temperatures in parts of the High Plains and Midwest were much below average for August, owing especially to much cooler than average afternoons in the region. Missouri had its seventh coolest August on record with an average temperature of 72.0°F, 4.0°F below average. It was the eighth coolest in Iowa and Kansas, the ninth coolest in Oklahoma, and the 10th coolest in Illinois and Nebraska.
- The contiguous U.S. average maximum (daytime) temperature during August was 84.3°F, 0.9F below the 20th century average, the 30th coolest on record and coolest since 2014. Above-average maximum temperatures were observed across the West. California, Oregon, and Washington each had a much warmer than average August maximum temperature on record. Below-average maximum temperatures were observed across many locations east of the Rocky Mountains to East Coast. Thirteen states across the Great Plains, Midwest, and Deep South had much-below-average maximum temperatures. No state had record cold maximum temperatures during August, but Louisiana's ranked as the second coolest.
- The contiguous U.S. average minimum (nighttime) temperature during August was 59.8°F, 0.7°F above the 20th century average, tying four other years as the 36th warmest on record. Above-average minimum temperatures spanned the West and Southeast with below-average conditions across the central United States. California, Nevada, and Oregon each had a record warm August minimum temperature.
- Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during August was 5 percent above average and ranked near the middle value in the 123-year period of record.
- During August there were 3,596 record warm daily high (1,363) and low (2,233) temperature records, which was more than 1.5 times the 2,277 record cold daily high (1,667) and low (610) temperature records.
- The August precipitation average for the contiguous U.S. was 3.34 inches, 0.7 inch above average, and the seventh wettest in the 123-year period of record.
- Texas was record wet, mostly due to powerful and slow-moving Hurricane Harvey and its remnants. Precipitation across the state averaged 6.57 inches, 4.26 inches above average. Louisiana averaged 12.64 inches, 8.0 inches above average, resulting in its second wettest August, 0.38 inch shy of the record set just in 2016, which also saw widespread very heavy rainfall and flooding.
- Locally in areas of Texas and Louisiana, precipitation amounts were historic due to Hurricane Harvey. At least 22 stations reported more than 500 percent of normal, or five times their normal rainfall for August. Monthly totals in excess of 40 inches were recorded by long-time NOAA observers in Lumberton and Beaumont, and at the Houston National Weather Service office.
- According to the August 29 U.S. Drought Monitor report, 11.8 percent of the contiguous U.S. was in drought, relatively unchanged since early August. Drought and abnormal dryness contracted across the Plains, in Alaska, Puerto Rico, and the Southwest and Mid-Atlantic regions. Drought and abnormal dryness expanded or intensified in the Pacific Northwest, northern Rockies, northern High Plains of Montana, and parts of the Midwest, Southeast, Kansas, Maine, and Hawaii.
- Climate Highlights — year-to-date (January-August)
Jan-Aug Average Temperature Departures
Jan-Aug Percent of Average Precipitation
- The year-to-date temperature averaged across the contiguous U.S. was 56.7°F, 2.8°F above the 20th century average. This ranks as the third warmest January-August period on record.
- Four Atlantic states – Florida, Georgia, and the Carolinas – were warmest on record for the period. No state fell in the 'Near Average' category or cooler.
- The contiguous U.S. average maximum (daytime) temperature during January-August was 68.5°F, 2.5°F above the 20th century average, the sixth warmest on record. Above-average maximum temperatures spanned the nation during the first eight months of the year. Only Washington State had a near-average year-to-date maximum temperature.
- The contiguous U.S. average minimum (nighttime) temperature during January-August was 44.8°F, 3.1°F above the 20th century average, ranking as the second warmest on record. Above-average minimum temperatures spanned the nation with every state having above-average conditions. Ten states across the Southwest and Southeast had record warm January-August minimum temperatures.
- Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during January-August was zero and the lowest value in the 123-year period of record.
- The year-to-date precipitation for the contiguous U.S. was 24.1 inches, 3.4 inches above average, and the wettest in the 123-year period of record.
- Ten states – scattered in parts of the South, Midwest, Northeast, and West – had precipitation totals among their 10 largest for the period. Only North Dakota (seventh driest) had a year-to-date precipitation considered much below average.
Other Weather and Climate Indicators
- The U.S. Climate Extremes Index (USCEI) for the summer was 80 percent above average and the third highest value on record. On the national scale, extremes in warm maximum and minimum temperatures were much above average as well as one-day precipitation totals. The USCEI is an index that tracks extremes falling in the upper or lower 10 percent of the record. The index covers land-falling tropical cyclones, temperature, precipitation, and drought across the contiguous U.S.
- On the regional scale, the CEI was much-above average for the Northeast, Ohio Valley, Southeast, South, Southwest, and West. Each of these regions observed elevated extremes in warm maximum and minimum temperatures. In the Northeast, the number of days with rain ranked as the second highest value. In the South, one-day precipitation totals ranked as the second highest. In the West, the spatial extent of wet conditions and one-day precipitation totals both ranked among the ten highest values on record.
**A comparison of the national temperature departure from average as calculated by NCDC's operational dataset (nClimDiv), the U.S. Historical Climatology Network (USHCN), and the U.S. Climate Reference Network (USCRN) is available on our National Temperature Index page.**
These regional summaries were provided by the six Regional Climate Centers and reflect conditions in their respective regions. These six regions differ spatially from the nine climatic regions of the National Centers for Environmental Information.
- Northeast Region: (Information provided by the Northeast Regional Climate Center)
- For the first time since March 2015, all twelve Northeast states had a monthly average temperature that was colder than normal. Departures ranged from 1.7 degrees F (0.9 degrees C) below normal in Pennsylvania and West Virginia to 0.6 degrees F (0.3 degrees C) below normal in Rhode Island. The Northeast's average August temperature was 66.8 degrees F (19.3 degrees C), 1.3 degrees F (0.7 degrees C) below normal. Summer was also colder than normal. The Northeast's average temperature of 67.3 degrees F (19.6 degrees C) was 0.3 degrees F (0.2 degrees C) below normal. Nine states experienced below-normal temperatures, with departures for all states ranging from 0.7 degrees F (0.4 degrees C) below normal in Vermont to 0.6 degrees F (0.3 degrees C) above normal in Delaware.
- August was a drier-than-normal month for the Northeast. The region picked up 3.56 inches (90.42 mm) of rain, which was 92 percent of normal. Eight states were drier than normal, one wrapped up the month at normal, and three were wetter than normal. Precipitation ranged from 45 percent of normal in Rhode Island, its 12th driest August, to 176 percent of normal in Delaware, its 16th wettest August. Summer ended on the wet side of normal for the region with 13.19 inches (335.03 mm) of rain, 107 percent of normal. Seven states received above-normal precipitation, with precipitation for all states ranging from 78 percent of normal in Maine to 147 percent of normal in Delaware, its 13th wettest summer.
- The U.S. Drought Monitor released on August 3 showed 2 percent of the Northeast, portions of northern and eastern Maine, was in a moderate drought. Abnormal dryness covered 8 percent of the region, including portions of New York's Long Island, southeastern New Hampshire, and southern, eastern, and northern Maine. Moderate drought and abnormal dryness expanded in Maine during the month. Abnormal dryness also expanded in southeastern New Hampshire, was introduced in southeastern Massachusetts, southern Rhode Island, and southern Connecticut, and lingered across Long Island. The U.S. Drought Monitor released on August 31 showed 5 percent of the Northeast was in a moderate drought and 8 percent of the region was abnormally dry.
- There were many days during August on which severe weather occurred. Nine tornadoes touched down in the region, four more than average (based on data from NOAA's Storm Prediction Center): three each in Pennsylvania and New York, two in Maine, and one in Maryland. The tornadoes, as well as strong thunderstorm-related winds, damaged buildings, downed wires, and snapped or uprooted over 1,000 trees. Lightning started several fires, and golf ball-sized hail also occurred. Storms also produced heavy rain. At least two events exceeded the 100-year return period, meaning rainfall of that magnitude has a 1% chance of occurring in a given year: 4.50 inches (114.30 mm) in 80 minutes in Burlington Township, New Jersey, on August 3 and a 1-day total of 8.25 inches (209.55 mm) on August 19 in Eastham, Massachusetts. Flash flooding occurred in multiple locations throughout the Northeast. Impacts included: impassable roads, stuck vehicles, water rescues, and flooded basements. In mid-August, Hurricane Gert caused high waves, rough surf, and rip currents along the Northeast coastline. Several beaches were closed.
- For more information, please go to the Northeast Regional Climate Center Home Page.
- Midwest Region: (Information provided by the Midwest Regional Climate Center)
- August temperatures were below normal across nearly all of the Midwest. Only a few areas in Ohio had temperatures near normal. For the region as a whole, temperatures averaged 68.1 degrees F (20.1 C) which was 2.8 degrees F (1.5 C) below normal. This was tied for the 14th coldest August for a record extending back to 1895. Missouri and Iowa ranked among the ten coldest August's on record (1895-Present). Nearly 500 combined daily low maximum and low minimum temperature records were broken or tied in August in the Midwest. Many of these records occurred during a very cool stretch from August 4-8. Temperatures dipped below freezing at several stations in the U.P. of Michigan and Minnesota Arrowhead for the first fall freeze of the season on the morning of August 25. This was near the earliest fall freeze on record for these areas. For the summer, the Midwest was slightly cooler than normal. Region-wide temperatures for June through August averaged 70.6 degrees F (21.4 C) which was 0.6 degrees F (0.4 C) below normal. However, many extremes were observed on both the cool and warm ends of the spectrum. More than 1,500 daily low and high temperature records were broken or tied across the region from June through August.
- August precipitation in the Midwest was largely limited to Minnesota, western Iowa, Missouri and Kentucky as dry conditions prevailed across most of the central Midwest. Region-wide, the Midwest had 3.80 inches (96.5 mm) which was 0.14 inches (3.5 mm) above normal. Areas of southwestern Minnesota, and western Missouri had more than twice the normal amount, while western Iowa, eastern southeastern Kentucky, northeastern Minnesota and the U.P. of Michigan had less than 75 percent of normal. Precipitation for the June through August period was 11.98 inches (304.3 mm) which was 0.02 inches (0.5 mm) above normal. However, many precipitation extremes occurred. Portions of Iowa, central Illinois and southern Lower Michigan had less than 75 percent of normal, while areas in Missouri, Ohio, Wisconsin and the U.P. of Michigan had more than 125 percent of normal. Rainfall often fell in extreme amounts with extended dry periods in between. More than 1,200 daily precipitation records were recorded in the June through August period, with at least 300 in each month.
- Severe weather occurred on 22 of the 31 days in August in the Midwest. However, only one day, August 18, had more than 50 storm reports. More than a dozen weak tornadoes were observed in Minnesota, Iowa, Illinois and Ohio from August 16-18. No injuries were reported with any of these tornadoes, though livestock were killed and crops were damaged from an EF-2 tornado in southwestern Minnesota on August 18.
- Drought persisted across western Iowa and northwestern Minnesota in August and worsened in southern Iowa. Drought coverage across the Midwest remained at less than 9 percent during the month. Extreme drought was added to several counties in south-central Iowa during the middle of August. Moderate drought was also added in central Illinois along with an expansion of abnormally dry conditions in southern Lower Michigan.
- The August 21 total solar eclipse traversed across several Midwest states. This was the first total solar eclipse in the Midwest region since 1925. Viewing of the eclipse along the path of totality was unobscured for most, as fair weather cumulus clouds decreased as solar radiation decreased. However, storms associated with a frontal boundary obscured viewing of the partial eclipse in Iowa, Minnesota, Wisconsin and northern Illinois.
- For further details on the weather and climate events in the Midwest, see the weekly and monthly reports at the Midwest Climate Watch page.
- Southeast Region: (Information provided by the Southeast Regional Climate Center)
- Temperatures were below average (driven primarily by unusually cool maximum temperatures) across interior portions of the Southeast region during August, while near-average to above-average temperatures were observed along much of the coastal plain. Over 80 percent of the 211 long-term (i.e., period of record equaling or exceeding 50 years) stations within the region observed August mean temperatures that were ranked outside their ten warmest or coolest values on record. However, well-above-average temperatures (driven largely by extremely warm minimum temperatures) occurred in portions of central and southern Florida, as well as Puerto Rico. Twelve long-term stations in these areas observed August mean temperatures that were ranked within their three warmest values on record, including Guayama 2 E, PR (1914-2017; warmest on record), Tampa, FL (1890-2017; third warmest), San Juan, PR (1899-2017; tied for third warmest), and Vero Beach, FL (1943-2017; tied for third warmest). With warmer-than-normal sea surface temperatures measured offshore, several stations near the coastline of Florida and Puerto Rico observed or tied their highest or second highest count of August days with a minimum temperature of at least 75 degrees F (23.9 degrees C), such as Melbourne, FL (1937-2017; 30 days) and Pensacola, FL (1880-2017; 29 days), or 80 degrees F (26.7 degrees C), such as San Juan, PR (1899-2017; 19 days) and West Palm Beach, FL (1888-2017; 9 days). Miami, FL (1896-2017) tied its warmest mean temperature for any month on record (85.7 degrees F; 29.8 degrees C), which was also observed last month for the first time in its 122-year period of record. In addition, Miami recorded its second greatest monthly count of 18 days with a minimum temperature at or above 80 degrees F, trailing only July 2017 (19 days). On two days during the month (5th and 31st), Miami tied its warmest minimum temperature for any month on record, at 84 degrees F (28.9 degrees C). The warmest weather of the month across the Southeast occurred from the 16th through the 18th, as the heat index (i.e., a measure of how hot it feels due to the combined effects of temperature and humidity) reached a maximum of 105 to more than 115 degrees F (40.6 to more than 46.1 degrees C) in parts of southeastern and east-central Georgia, the eastern half of South Carolina, and southeastern North Carolina. In contrast, the coolest weather of the month occurred on the 1st, as a continental high pressure system ushered in unseasonably cool, dry air from the north. Daily minimum temperatures fell below 65 degrees F (18.3 degrees C) as far south as northern Florida, while much of North Carolina and Virginia recorded minimum temperatures ranging from the middle 40s F to the upper 50s F (5 to 17 degrees C). A solar eclipse occurred over the region during the afternoon of the 21st, with the 70-mile-wide path of totality extending southeastward from far western North Carolina to the central coast of South Carolina. Some of the greatest temperature drops that were recorded from the rapid reduction in solar radiation included 11 degrees F (6.1 degrees C) at Athens-Ben Epps Airport, GA and 9 degrees F (5 degrees C) at Huntsville International Airport, AL, Greenville-Spartanburg International Airport, SC, and Asheville Regional Airport, NC.
- Precipitation was highly variable across the Southeast region during August, with several wet extremes recorded. Unusual dryness was found in portions of east-central and southeastern Florida, the Florida Keys, the southern half of Georgia, central South Carolina, and south-central North Carolina, where monthly precipitation totals were 2 to 5 inches (50.8 to 127 mm) below normal. In contrast, the wettest locations were found primarily across broad portions of Alabama, the western half of the Florida Panhandle, west-central and southwestern Florida, the coast of the Carolinas, and eastern Virginia. Monthly precipitation totals ranged from 3 to more than 10 inches (76.2 to more than 254 mm) above normal in these areas. Several long-term stations in Florida observed their wettest or second wettest August on record, including Naples (1942-2017; 21.04 inches, 534 mm), Sarasota-Bradenton (1911-2017; 20.97 inches, 533 mm), Pensacola (1880-2017; 20.44 inches, 519 mm), and Fort Myers (1892-2017; 16.95 inches, 431 mm). This was also the third wettest month on record for Naples, trailing only June 2017 (24.29 inches; 617 mm) and July 1985 (21.49 inches; 546 mm). Monthly precipitation ranged from well below normal to well above normal across Puerto Rico and the U.S. Virgin Islands. Numerous heavy rainfall events occurred during the month, with 175 reports of flooding across the region. On the 1st, training thunderstorms produced heavy rainfall and flash flooding in portions of downtown Miami, FL and nearby Miami Beach. The COOP station in Miami Beach (1927-2017) observed its wettest August day and ninth wettest day for any month on record, with 6.50 inches (165 mm) of precipitation. Numerous vehicles were stranded on flooded roadways, while floodwater entered many homes and businesses in these areas. The heavy rainfall occurred during a period of rising tides around Miami, which prevented storm drains from channeling the floodwater into Biscayne Bay for several hours. On the 10th, slow-moving thunderstorms produced heavy rainfall and flash flooding across the Montgomery, AL metropolitan area, with numerous reports of flooded roads. The ASOS station at Montgomery Regional Airport recorded 4.84 inches (123 mm) of precipitation in just one hour, which corresponds to an average recurrence interval of approximately 1,000 years at this location. Multiple rounds of torrential rainfall occurred across the Huntsville, AL metropolitan area on the same day, with many impassable roads in Madison County due to flooding. Floodwater entered several homes, and a few partially submerged vehicles were reported across the county. A personal weather station near Hazel Green, AL recorded 6.40 inches (163 mm) of precipitation in only 3 hours, which occurs once every 500 years on average at this location. From the 23rd through the 28th, a nearly stationary low pressure system produced multiple rounds of heavy rainfall across southwestern Florida. Some of the highest 6-day precipitation totals included 18.86 inches (479 mm) at Sarasota-Bradenton International Airport, 18.42 inches (468 mm) at the COOP station in Venice, 16.55 inches (420 mm) at a CoCoRaHS station in Cape Coral, and 14.10 inches (358 mm) at Page Field Airport in Fort Myers. Sarasota-Bradenton observed its highest 1-day and 2-day precipitation totals for August and its third highest 1-day and 2-day precipitation totals for any month on record, with 8.12 inches (206 mm) on the 26th and 12.44 inches (316 mm) from the 26th through the 27th. On the 27th, a resident of Sarasota was killed after driving his vehicle into deep floodwater, while over 60 homes were flooded in a Bradenton neighborhood, requiring at least 26 people to be evacuated. From the 29th through the 30th, Tropical Storm Harvey produced heavy rainfall and flooding across southern Alabama and the western half of the Florida Panhandle. Some of the highest 2-day precipitation totals in these areas included 9.59 and 8.47 inches (244 and 215 mm) at CoCoRaHS stations near Foley, AL and Perdido Key, FL, respectively.
- There were 159 severe weather reports across the Southeast during August, which is about 50 percent of the median monthly frequency of 323 reports during 2000-2016. At least one severe weather report was recorded on 23 days during the month, but only six of these days had more than 10 reports. Strong thunderstorm winds accounted for over 90 percent (147 of 159) of the severe weather reports during August and were responsible for 6 injuries across the region. On the 3rd, a thunderstorm microburst with wind gusts of 50 to 60 mph damaged a bar on the Cocoa Beach Pier in Florida, resulting in 3 minor injuries. On the 23rd, thunderstorm wind gusts estimated at 60 to 70 mph caused a large tree branch to fall onto a vehicle in Smithfield, NC, injuring an entrapped occupant. In addition, several businesses and carports sustained structural damage, while downed trees and power lines were reported across the town. A total of 9 tornadoes (5 EF-0s, 2 EF-1s, 2 EF-2s) were confirmed across the region during the month, which is near the median frequency of 8 tornadoes observed during August. On the 31st, the remnant circulation of Hurricane Harvey spawned three tornadoes in Alabama, including both of the EF-2s observed during the month. One of these EF-2 tornadoes caused 6 injuries along its 31-mile track across three counties in Alabama. The greatest damage from this tornado occurred in the town of Reform, where several single-family houses and a mobile home were destroyed. One of the single-family homes was completely swept off its foundation, with 4 residents sustaining minor injuries. Lightning strikes were responsible for 1 fatality and 9 injuries in Alabama and Florida, collectively. On the 26th, a group of six men were struck by lightning while on the beach at Gulf Shores, AL. All six men were injured, but a 24-year-old man later died after being transported to a hospital in Birmingham. On the 18th, lightning ignited a fire at an apartment complex in Jacksonville, FL, with six units damaged and twelve residents displaced.
- Drought conditions (D1 and greater) were not observed across the mainland portion of the Southeast region during August. However, below-average precipitation caused abnormally dry (D0) conditions to persist across central portions of North Carolina and Virginia, with additional development occurring in areas of South Carolina and Georgia during the second half of August. A narrow strip of moderate (D1) drought persisted along the southwestern coast of Puerto Rico, but drought conditions were removed from the south-central portion of the island. During the first half of the month, croplands and pastures were aided by mild temperatures and near-average to above-average rainfall across much of the region, but excessive wetness in some areas prevented agricultural producers from harvesting crops and cutting hay. Favorable weather conditions, including consistent rainfall and few days of extreme heat, throughout much of August and summer contributed to exceptional yields of corn in Alabama and peanuts in Georgia. However, some farmers in Alabama had to spray fungicides regularly in their soybean and peanut fields, as abundant precipitation increased fungal disease pressure on these crops. In addition, persistent rainfall during early August caused wine grapes to rot across northern Georgia, despite a steady application of fungicides in some vineyards. Coupled with a multi-day period of excessive heat, predominately dry weather during the latter half of the month stressed crops and pastures across central portions of the Carolinas and Virginia, as well as southern Georgia. Many livestock producers in central Virginia had to begin a supplemental feeding for their herds due to insufficient grazing conditions, with some producers preparing to purchase hay reserves for autumn and winter.
- For more information, please go to the Southeast Regional Climate Center Home Page.
- High Plains Region: (Information provided by the High Plains Regional Climate Center )
- The latter part of the summer turned cooler for much of the High Plains region, as August temperatures were largely below normal, particularly across the eastern part of the region. Several locations in Nebraska did not reach 90.0 degrees F (32.2 degrees C) the entire month, which is quite rare for the state. Many people enjoyed the welcomed break from the summertime heat; however, the cool temperatures have producers concerned about drying crops down for harvest and the risk of an early frost or freeze that would be especially detrimental to late-planted and replanted crops. As for precipitation, it was a mix of wet and dry conditions across the region. The excessive wetness throughout the Dakotas and Nebraska was particularly impactful, as heavy rains relieved drought conditions across these areas but caused flash flooding as well. As for the summer season, it was warm and dry across the majority of the High Plains with the exception of eastern parts of the region where summer temperatures were slightly below normal.
- On August 21st, portions of the High Plains were treated to an extremely rare event - a total solar eclipse. This event drew an enormous amount of attention across the country, as total solar eclipses do not pass through the U.S. very often. Thousands of people traveled to the High Plains to witness this event, as the region was an attractive venue for viewing due to its low population and often clear skies. The path of totality passed through the heart of Wyoming and Nebraska, as well as extreme northeastern Kansas. Total solar eclipses impact the weather locally. The rapid decrease in solar radiation leads to a decrease in temperature, which in turn increases the relative humidity. Weather stations in the path of the eclipse captured these changes in the weather in the moments before, during, and after the eclipse. For instance, the air temperature decreased as much as 9.0 degrees F (5.0 degrees C) in the path of totality in western Wyoming. NOAA put together a website where you can learn more about how the eclipse impacted climate at the U.S. Climate Reference Network (USCRN) stations, which can be found here: http://www.atdd.noaa.gov/crn-eclipse/.
- After a warm start to the summer season, the temperature pattern turned cooler in August, with much of the region experiencing below-normal temperatures. Temperatures ranged from near normal in the western High Plains to 4.0-6.0 degrees F (2.2-3.3 degrees C) below normal in the eastern High Plains. Several locations across South Dakota, Nebraska, and Kansas had a top 10 coolest August on record.
- Nebraska was particularly cool, as the temperature did not reach 90.0 degrees F (32.2 degrees C) in August in Grand Island, Norfolk, or Lincoln. In fact, this was the first time on record that Grand Island and Norfolk did not reach the 90s in August, and both locations had their coolest maximum temperature on record for August. The maximum temperature was 89.0 degrees F (31.7 degrees C) on the 15th in Grand Island and 87.0 degrees F (30.6 degrees C) on the 1st in Norfolk. In Lincoln, the maximum temperature in August was 89.0 degrees F (31.7 degrees C) on the 15th, and August 1915 was the only other time on record that the temperature did not reach the 90s.
- While many would welcome the break from summertime temperatures, the cooler August weather has negative implications for crops. For instance, Growing Degree Days (GDDs) accumulate less quickly during cooler weather, which slows the progress of crop growth and delays crops from reaching maturity. This is particularly a concern for late-planted and replanted crops because an early frost or freeze would be detrimental. With the trend of cooler temperatures continuing well into September, this issue is certainly worth keeping an eye on.
- The precipitation pattern in August indicated mostly dry conditions in the western High Plains and across much of Kansas with wetter conditions to the east. While the dryness was not record-breaking, wet weather across parts of the Dakotas and Nebraska led to several locations having a top 10 wettest August on record, including Bismarck, ND (5th wettest), Williston, ND (6th wettest), Grand Island, NE (9th wettest), and Norfolk, NE (10th wettest).
- The wettest region was northern and central Nebraska, an area where drought developed during the early part of the summer as a result of a lack of precipitation. Although the heavy precipitation essentially ended the drought, storms continuously pummeled the area during August and caused flash flooding, high winds, and damaging hail. Custer County, Nebraska, which includes the town of Broken Bow, was hit particularly hard with these storms. According to the Associate State Climatologist for Nebraska, three hail events occurred in the Broken Bow area on the 13th, 15th, and 19th, causing widespread hail damage to crops in the region. On the 15th, very heavy rain fell across the northwestern portion of Custer County and, according to CoCoRaHS reports, the area received approximately 4.00-7.00 inches (102-178 mm) of rain. By the end of August, parts of central Nebraska had received over 9.00 inches (229 mm) of rain, which is more than one-third of the region's normal annual precipitation. One concern that has come about as a result of recent wetness is the drying down of crops for harvest. Typically, crops are dried naturally in Nebraska due to expected low relative humidity values in the fall. However, with the extra moisture present, propane may need to be used for drying, which could lead to a shortage of supply and an increase in cost.
- Looking at precipitation for the summer season, it was mostly a dry summer across the region. Salina, Kansas had its 4th driest summer on record, while Valentine, Nebraska and Minot, North Dakota had their 5th driest summers. Despite the presence of drought this summer across parts of the Dakotas, excessive precipitation in August brought up summer precipitation totals and prevented many locations from having record-breaking dryness for the season. Amidst the dryness, there were pockets of wetter conditions across central Nebraska, southeastern Colorado, and extreme eastern Kansas. For instance, Alamosa, Colorado had its 7th wettest summer on record.
- Streamflow conditions varied widely across the High Plains region during August. Wet conditions in the Wind River Basin in Wyoming kept streamflows above normal, as they have been for most of the summer. The heavy precipitation that occurred across central Nebraska and extreme eastern Kansas significantly increased streamflow in these areas, and some streams were running very high. Flows were highest on the Elkhorn River and the Middle Loup River in Nebraska, and the Blue River in Kansas. Heavy rains brought drought relief to parts of the Dakotas and vastly improved streamflows across the area, with some streams actually running above normal for the time of year. However, prolonged dryness continued along the Kansas/Nebraska border and across northern Kansas, resulting in flows along several streams running below normal.
- Thanks to cooler temperatures and heavy rainfall during the month of August, drought conditions eased in portions of the High Plains. According to the U.S. Drought Monitor, the area experiencing abnormally dry or drought conditions (D0-D4) decreased from approximately 62 percent to 50 percent, and only one quarter of the region was in drought (D1-D4) by the end of the month. Beneficial rainfall occurred across parts of the Dakotas and northern Nebraska where it was needed the most. These areas received greater than 200 percent of normal precipitation during August. The rainfall helped with the green up of pastures and improvement of soil moisture and row crop conditions.
- However, other areas of the region missed out on the rainfall. For instance, central Kansas was dry this summer, receiving less than 70 percent of normal precipitation. As a result, moderate drought (D1) expanded in the area during August. Conditions also worsened in southwestern South Dakota, where extreme drought conditions (D3) expanded.
- While on the periphery of the High Plains region, it is important to note that Montana has been dealing with impacts from the Northern Plains drought. Conditions worsened across the state in August, as it was very dry throughout most of the month. Most of the state's topsoil moisture continued to be short to very short, and over two-thirds of its pastureland was in poor to very poor condition. Dry lightning has sparked fires and burned thousands of acres, and the irrigation season ended early in some locations.
- For more information, please go to the High Plains Regional Climate Center Home Page.
- Southern Region: (Information provided by the Southern Regional Climate Center)
- August had below to near normal temperatures for most of the region. There were areas of 4 to 6 degrees F (2.22 to 3.33 degrees C) below normal in northern Texas, northern Arkansas, and northern and western Oklahoma. There was a small area in northwestern Arkansas that reported 6 to 8 degrees F (3.33 to 4.44 degrees C) below normal temperatures. Most of Oklahoma, Arkansas, northern Texas, northwestern Louisiana, northeastern Mississippi, and western and central Tennessee reported 2 - 4 degrees F (1.11 to 2.22 degrees C) below normal temperatures. There were clusters in Mississippi, southern Louisiana, and southern Texas that were near to slightly above normal temperatures. In extreme southern Texas there were two clusters of 2 to 4 degrees F (1.11 to 2.22 degrees C) above normal temperatures. The statewide monthly average temperatures were as follows: Arkansas reporting 76.80 degrees F (24.89 degrees C), Louisiana reporting 81.00 degrees F (27.22 degrees C), Mississippi reporting 79.40 degrees F (26.33 degrees C), Oklahoma reporting 77.20 degrees F (25.11 degrees C), Tennessee reporting 74.60 degrees F (23.67 degrees C), and Texas reporting 80.60 degrees F (27.00 degrees C). The state-wide temperature rankings for August are as follows: Arkansas (seventeenth coldest), Louisiana (thirty-sixth coldest), Mississippi (thirty-third coldest), Oklahoma (ninth coldest), Tennessee (twenty-third coldest), and Texas (thirtieth coldest). All state rankings are based on the period spanning 1895-2017.
- Precipitation values for the month of August were above normal for most of the Southern Region. Due to Hurricane Harvey, parts of western Louisiana and northeastern and southeastern Texas reported 400 percent or more of normal precipitation. Some areas in southeastern Texas reported 800 percent of normal precipitation. Central and southern Oklahoma, western and southern Arkansas, northern and eastern Texas, and most of Louisiana reported 200 - 400 percent of normal precipitation. There were also clusters in western Tennessee and northern, western, and southern Mississippi that reported 200 - 400 percent of normal precipitation. There were clusters of 50 - 75 percent of normal precipitation in southern Tennessee, and central and southwestern Texas. A few areas in southwestern Texas reported 2 - 25 percent of normal precipitation. The state-wide precipitation totals for the month are as follows: Arkansas reporting 5.95 inches (151.13 mm), Louisiana reporting 12.64 inches (321.06 mm), Mississippi reporting 6.90 inches (175.26 mm), Oklahoma reporting 6.20 inches (157.48 mm), Tennessee reporting 4.67 inches (118.62 mm), and Texas reporting 6.57 inches (166.88 mm). The state precipitation rankings for the month are as follows: Arkansas (tenth wettest), Louisiana (second wettest), Mississippi (eighth wettest), Oklahoma (third wettest), Tennessee (twenty-third wettest), and Texas (first wettest). All state rankings are based on the period spanning 1895-2017.
- Over the month of August 2017, drought conditions improved for most parts of the region, such as areas in Oklahoma and central and northern Texas. In contrast, drought conditions worsened in southern Texas. Currently, there are areas of moderate drought present in southwestern Texas. At this time there are no areas of severe, extreme, or exceptional drought. There are a few small areas of abnormally dry conditions in southern Texas, northern Oklahoma, and northeastern Mississippi.
- Hurricane Harvey made landfall on August 25, 2017, in southeastern Texas, with major hurricane status. The hurricane stalled and dropped over 50 inches (1270 mm) of rain in parts of southeast Texas, which broke many records throughout the area. John Nielsen-Gammon, Texas state climatologist, reported that Hurricane Harvey averaged 34.72 inches (881.89 mm) of rain in the southeastern Texas region over five days, which broke the previous record of 21.39 inches (543.31 mm) for that region set in 1899. Some other reports coming in throughout the southeastern Texas region were Cedar Bayou reporting 52 inches (1320.8 mm) of rain, Houston reporting 43 inches (1092.2 mm) of rain and Beaumont receiving more than 45 inches (1143 mm) of rain. This event caused at least 60 deaths throughout the area.
- On August 5, 2017, there were four tornadoes reported in Oklahoma. One tornado caused five injuries in Tulsa, Oklahoma. There were 23 strong wind events throughout Oklahoma and Texas. A wind gust of 104 mph (167.37 kph) was reported in Rogers, Oklahoma.
- On August 6, 2017, there were 13 wind events reported in Texas. One wind event caused an 18-wheeler to become overturned in Haskell, Texas.
- On August 13, 2017, there was a tornado reported in Potter, Texas. Potter, Texas also reported a 78 mph (125.53 kph) wind gust.
- On August 16, 2017, there were 21 wind events reported throughout Texas, Oklahoma, and Mississippi. Noble, Oklahoma reported a wind gust of 76 mph (122.31 kph).
- On August 18, 2017, there were four hail and eleven wind reports in northwestern Arkansas. There were trees and power lines reported down in Logan, Arkansas.
- On August 25, 2017, there were nine tornadoes reported in southeastern Texas resulting from Hurricane Harvey. In Brazoria, Texas there were reports of damaged buildings and vehicles from a tornado.
- On August 26, 2017, there were 14 tornadoes reported throughout southeastern Texas and southwestern Louisiana as a result of Hurricane Harvey. In Cameron, Louisiana a tornado caused a camper to be flipped on its side and roof damage to some structures.
- On August 27, 2017, there we seven reports of tornadoes as a result from Harvey throughout Texas and Louisiana. In Harris, Texas a tornado caused a tree to fall through a roof in the fifth ward.
- On August 29, 2017, five tornadoes were reported throughout Louisiana and Mississippi.
- On August 30, 2017, seven tornadoes were reported in southern Mississippi. In Forrest, Mississippi, a tornado caused roofs to be torn off of two businesses.
- On August 31, 2017, there were five tornadoes reported in northeastern Mississippi. In Itawamba, Mississippi, numerous trees were downed and several mobile homes were damaged from a tornado.
- For more information, please go to the Southern Regional Climate Center Home Page.
- Western Region: (Information provided by the Western Region Climate Center)
- August temperatures were above normal for the coastal states and western Great Basin and generally near normal elsewhere. The Pacific and Inland Northwest were drier than normal, while parts of California and the Great Basin observed well above normal precipitation associated with monsoon thunderstorms.
- This month was drier than normal in the Pacific Northwest, however, it should be noted that August is typically one of the driest months of the year in this area. Seattle, Washington, reported 0.02 in (0.5 mm), 2% of normal and the 3rd driest August since records began in 1945. Seattle saw its longest run of dry days on record this year, with 55 consecutive days of no measurable precipitation ending August 11. Roseburg, Oregon, received no measurable precipitation this month, as is 21 other years in its 119-year record. Normal August rainfall is 0.47 in (12 mm) at Roseburg. Drier than normal conditions were also present across northern Idaho and Montana, where August precipitation is more significant. Great Falls reported 0.06 in (1.5 mm), 4% of normal and the 4th driest August since records began in 1937. Montana saw expansion and increase in severity of drought conditions in the US Drought Monitor this month; more than 90% of the state is now experiencing moderate to exceptional drought.
- Precipitation was variable across the area typically impacted by North American Monsoon activity, with scattered areas of above, below, and near normal precipitation. Eastern New Mexico stood out for above normal precipitation; Tucumcari reported 4.12 in (105 mm), 134% of normal and the 10th wettest August since records began in 1941. Eastern and southern California as well as western Nevada saw scattered areas of well above normal precipitation. During the first few days of the month and again at the end of the month, monsoonal moisture moved into the region. A weak cutoff low mid-month also helped create favorable thunderstorm conditions. In southern California, Sandberg, typically dry this time of year, observed 0.88 in (22 mm) for the month, 2900% of normal and the second wettest August since records began in 1948. Elsewhere in southern California, Palm Springs reported 0.71 in (18 mm) for the month, 209% of normal. In the lee of the Sierra Nevada, Bodie, California, received 1.61 in (41 mm), 358% of normal and the 7th wettest since records began in 1895.
- August began with well above normal temperatures, especially in the Pacific Northwest, associated with an amplified ridge. The passage of a couple low-pressure systems helped to moderate temperatures in the coastal states mid-month, and a building ridge raised temperatures again over the last week of the month. Medford, Oregon, reached 112 F (44.4 C) on August 2, the third highest temperature recorded since records began in 1911. Medford had its warmest August on record at an average 78.1 F (25.6 C), 4.4 F (2.4 C) above normal. Seattle, Washington, reported its 2nd warmest August on record and 3rd warmest month since records began in 1945 at 70.3 F (21.3 C), 4.2 F (2.3 C) above normal. Further south, Redding, California, observed its 2nd warmest August in a 125-year record at 85.9 F (29.9 C), 6.1 F (3.4 C) above normal. To the east, Reno, Nevada, reported its second warmest August as well at 78.7 F (25.9 C), 5.5 F (3.1 C) above normal. Records for Reno began in 1937. In southern California, Bakersfield reported its warmest August on record at 87.9 F (31 C), 5.5 F (3.1 C) above normal. Records for Bakersfield began in 1937.
- In Alaska, precipitation was near to well above normal for most of the state, though some locations in the Southcentral region observed below normal precipitation. For example, Cordova logged 15.51 in (394 mm), 175% of normal, while Gulkana recorded 1.07 in (27 mm), 59% of normal. Temperatures were near normal across much of Alaska, except for the Interior region, where temperatures were 1-3 F (0.5-1.5 C) above normal at some locations. Fairbanks reported an average 58.8 F (14.9 C), 2.7 F (1.5 C) above normal. In Hawaii, August temperatures were above normal throughout the state. Lihue, Kauai, reported its all-time warmest month on record at 82.7 F (28.2 C), 3 F (1.7 C) above normal. Precipitation was variable across the state, but most locations reported near normal to slightly below normal precipitation. Kahului, Maui, recorded 0.25 in (9 mm), 52% of normal. Several locations on Oahu reported above normal precipitation; Honolulu recorded 1.85 in (47 mm), 330% of normal.
- August 3: Flash flooding in southern California: Intense thunderstorms produced flash flooding in areas of California's Inland Empire in association with abundant monsoon moisture over the area. The flooding caused road closures and several rescues from vehicles, including evacuation of 200 Metrolink train passengers in the Acton area.
- August (periods throughout month): Poor air quality in Pacific Northwest: Smoke from wildfires in British Columbia and within the region produced extended periods of poor air quality. Some of the greatest impacts were seen in central/eastern Washington as well as the Seattle area, where air quality reached levels considered 'unhealthy' at times.
- August (all month): Wildfires impact West: National Preparedness Level reached 5, the highest level, this month. In Oregon, the Chetco Bar Fire near Brookings burned over 142,000 acres (57,000 hectares) and destroyed 5 homes. In northern California, the Ponderosa Fire near Oroville has burned over 4,000 acres (1,600 hectares) and destroyed 32 homes. The Rice Ridge Fire near Seeley Lake, Montana, burned roughly 40,000 acres (16,000 hectares) by the end of August and prompted the evacuation of nearly all residents of Seeley Lake. Fires have produced hazardous air quality in nearby communities in many western locations.
- For more information, please go to the Western Regional Climate Center Home Page.