- For September, the average contiguous U.S. temperature was 67.8°F, 3.0°F above the 20th-century average, the fifth-warmest September in the 127-year period of record. For the year-to-date, the contiguous U.S. temperature was 57.0°F, 1.9°F above the 20th-century average, ranking 10th warmest in the January-September record.
- September temperatures were above average from the West Coast to the Great Lakes and into New England. Colorado and Rhode Island ranked third warmest on record for the month while five additional states across the West and Northeast ranked in the top five for September. Temperatures were near average across parts of the Northwest, Gulf Coast and Southeast.
- The nationally averaged maximum temperature (daytime highs) was warmer than average during September at 81.2°F, 3.4°F above average, ranking seventh warmest in the 127-year record. Colorado ranked record warmest for maximum temperatures in September, while much of the West, Plains, Great Lakes, Northeast and Mid-Atlantic experienced above-average daytime high temperatures for the month. Portions of the Gulf Coast and Tennessee Valley had below-average daytime high temperatures.
- The nationally averaged minimum temperature (overnight lows) during September was 54.5°F, 2.6°F above average, ranking ninth warmest in the 127-year record. Massachussetts and Rhode Island ranked third warmest on record with much of the CONUS experiencing above-average overnight low temperatures during September. Portions of the Northwest, Great Lakes and from the Deep South to the Carolina coast experienced near average overnight minimum temperatures.
- Alaska had a statewide average temperature of 39.3°F, 1.3°F below the long-term average and ranked in the coolest one-third of the 97-year record. Temperatures were below average across much of the state with near-average temperatures dominating the North Slope and portions of the northern interior regions. Temperatures were above average across the Central Panhandle.
- As of October 5, there were 5,272 daily warm high (2,953) and low (2,319) temperature records tied or broken during September. This was nearly six times the 881 cold daily high (487) and low (394) temperature records set during the month.
- Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during September was 111 percent of average and ranked in the middle one-third of the 127-year period of record.
- The September precipitation total for the contiguous U.S. was 2.33 inches, 0.16 inch below average, ranking in the middle one-third of the 127-year period of record.
- Precipitation was above average across portions of the Northwest, Southwest, northern and central Plains and from the central Gulf Coast to New England. A series of atmospheric river events during the second half of September contributed to the above-average precipitation received across the Northwest. Resulting primarily from precipitation received as a result of the remnants of Hurricane Ida, Pennsylvania had its seventh-wettest September while Massachusetts ranked eighth wettest. For additional information on the record rainfall across portions of the Northeast, read the NRCC highlights below. Precipitation was below average across much of the northern Rockies, Deep South and Midwest. Oklahoma had its ninth-driest September on record.
- Alaska’s average of 4.36 inches of precipitation in September was 0.21 inch below average and ranked in the middle one-third of the 97-year record. Precipitation was above average across the North Slope and the South Panhandle regions and below average from Bristol Bay to the Northeast Gulf region. The 2021-2022 Alaska snow season got off to a healthy start in September with some regions receiving the most snow seen in September since the late 1970s. With fall temperatures firmly in place, it is likely that most of this snow will stick around for much of the duration of the cold season.
- According to the September 28 U.S. Drought Monitor, approximately 47.8 percent of the contiguous U.S. was in drought, up about 1 percent from the end of August. Drought conditions expanded or intensified across portions of the Midwest and central Plains and rapidly developed across the southern Plains during the second half of September. Drought severity and/or coverage lessened across parts of the West, northern Plains and New England.
- The western U.S. continues to battle an active fire season in 2021.
- By the end of September, almost six million acres were consumed across the U.S. This is approximately 500,000 acres less than the year-to-date 10-year (2011-2020) average.
- The KNP Complex wildfires erupted in Sequoia and Kings Canyon National Parks in California during September, threatening some of the oldest and largest sequoia trees in the world. To help protect these trees, firefighters wrapped their bases in fire proof aluminum blankets.
- On September 21, the Wildfire Preparedness Level was reduced to PL4, indicating that officials expected fire activity and demand on resources to continue declining as the wildfire season begins to wane. By September 28, officials further reduced the Preparedness Level to PL3.
- The Atlantic Basin hurricane season continued to be active with 20 named storms identified during the first nine months of 2021. In September alone, nine new named storms formed — Larry, Mindy, Nicholas, Odette, Peter, Rose, Sam, Teresa and Victor.
- Remnants of Hurricane Ida combined with a frontal system and brought unprecedented rainfall to parts of the Northeast on September 1. Flash Flood Emergencies were declared for the first time on record across parts of New Jersey and New York. Flash flooding, strong tornadoes and many fatalities resulted.
- Tropical Storm Mindy made landfall on St. Vincent Island, Florida, on September 8 and quickly moved across Georgia and into the Atlantic Ocean causing minimal damage.
- Hurricane Nicholas made landfall near Sargent Beach, Texas, on September 14 and drifted slowly toward Louisiana over the next several days, bringing flooding rainfall to parts of the Gulf Coast already saturated from Hurricane Ida.
Billion-Dollar Weather and Climate Disasters
- NCEI updated the 2021 billion-dollar weather and climate disaster dataset to include 10 additional events for 2021 — five severe storm events, four tropical cyclone events and one wildfire event.
- Through the end of September, 18 weather and climate disaster events have been identified with losses exceeding $1 billion each across the U.S. during 2021. These events include one drought/heat wave event, two flooding events, nine severe storm events, four tropical cyclone events, one wildfire event and one winter storm/cold wave event. This is four events shy of the 2020 annual record of 22 events.
- The U.S. disaster costs for the first nine months of 2021 are $104.8 billion, already surpassing the disaster costs for all of 2020 ($100.2 billion, inflation-adjusted).
- Through September, disasters in 2021 have also caused more than twice the number of fatalities than from all the events that occurred in 2020.
- Hurricane Ida is the most costly disaster to-date in 2021 — exceeding $60 billion — and will be ranked among the top-five most costly hurricanes on record (since 1980) for the U.S. Ida’s total cost will likely increase further, which will be reflected in our end-of-year report.
- Since records began in 1980, the U.S. has sustained 308 separate weather and climate disasters where overall damages/costs reached or exceeded $1 billion (based on the CPI adjustment to 2021) per event. The total cost of these 308 events exceeds $2.085 trillion. Disaster costs over the last five years (2017-2021) will exceed a record $700 billion, reflecting the increased exposure and vulnerability of the U.S. to extreme weather and climate events.
- For the year-to-date, the contiguous U.S. temperature was 57.0°F, 1.9°F above the 20th-century average, ranking 10th warmest in the January–September record.
- Year-to-date temperatures were above average across the West, the northern and central Plains, Great Lakes, Northeast, Mid-Atlantic and portions of the Southeast. Maine had its second-warmest January-September on record while California ranked third warmest. Temperatures were below average across parts of the Deep South.
- The contiguous U.S. average maximum (daytime) temperature during January-September was 69.0°F, 1.7°F above the 20th-century average, ranking 14th warmest in the 127-year record. Above-average maximum temperatures were observed across the West, northern Plains, Great Lakes, Northeast and portions of the Southeast. California ranked third warmest on record. Below-average maximum temperatures were observed from the Deep South to the middle-Mississippi River Valley and into portions of the Southeast.
- The contiguous U.S. January-September minimum (nighttime) temperature was 44.9°F, 2.1°F above average, and ranked eighth warmest on record. Above-average minimum temperatures were observed across most of the CONUS. Minimum temperatures averaged across Maine were second warmest for this year-to-date period with New Hampshire, Massachussets and Rhode Island ranking third warmest. Portions of the Deep South ranked near average for this period.
- Year-to-date temperatures averaged across Alaska were near normal. Above-average temperatures observed across the southwestern and northeastern portions of the state, while most of Alaska had near-average temperatures over the first nine months of 2021.
- Based on REDTI, the contiguous U.S. temperature-related energy demand during January-September was 77 percent of average and ranked in the lowest one-third third of the 127-year period of record.
- For the year-to-date, the national precipitation total was 23.58 inches, 0.38 inch above average, ranking in the middle one-third of the January-September record.
- January-September precipitation was above average across portions of the Southwest and from the Gulf Coast to the Ohio Valley and into the Northeast. Mississippi had its third-wettest year-to-date period while Louisiana ranked fourth wettest on record. Precipitation was below average from the West Coast to the northern Plains. Montana had its third-driest year-to-date on record, while North Dakota was fifth driest.
- The 2021 western U.S. water year, spanning October 2020 to September 2021, ended with much of the region experiencing below-average precipitation. It was the driest water year on record for portions of California including Redding, Red Bluff and Sacramento Executive Airport.
- For Alaska as a whole, January-September precipitation was above average. Precipitation was average to below average from the Aleutians to the Northeast Gulf and above average across much of the remaining portions of the state.
- The USCEI for the year-to-date was 59 percent above average and ranked 10th highest in the 112-year period of record. Extremes in warm maximum and minimum temperatures as well as dry PDSI contributed to this elevated value.
- On the regional scale, the Northeast ranked second highest and the West ranked third highest on record. Elevated extremes observed across the Northeast were due to widespread warm maximum and minimum temperatures, extremes in 1-day precipitation and the number of days with precipitation. For the West, widespread extremes in warm maximum and minimum temperatures as well as dry PDSI and days without precipitation contributed to the elevated CEI value.
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)
- The Northeast had its 15th warmest September in 127 years of recordkeeping with an average temperature of 63.2 degrees F (17.3 degrees C), 1.6 degrees F (0.9 degrees C) above normal. September average temperature departures for the 12 Northeast states ranged from 0.4 degrees F (0.2 degrees C) above normal in West Virginia to 2.5 degrees F (1.4 degrees C) above normal in Massachusetts and Rhode Island. This September ranked among the 20 warmest on record for nine states: Rhode Island, fourth warmest; Massachusetts, fifth warmest; Maine, sixth warmest; Connecticut and New Hampshire, ninth warmest; New Jersey and Vermont, 11th warmest; Delaware, 13th warmest; and Maryland, 20th warmest.
- September 2021 ranked as the 13th wettest September since 1895, with the region picking up 5.71 inches (145.03 mm) of precipitation, 142 percent of normal. Ten of the 12 Northeast states were wetter than normal in September, with precipitation ranging from 96 percent of normal in Delaware to 187 percent of normal in Connecticut. This September was among the 20 wettest on record for seven states: Pennsylvania, seventh wettest; Massachusetts, eighth wettest; Connecticut and Maine, ninth wettest; Rhode Island, 10th wettest; New Jersey, 15th wettest; and Maryland, 17th wettest. Newark, New Jersey, recorded its wettest September on record with 10.50 inches (266.70 mm) of rain, beating the old record of 10.28 inches (261.11 mm) from 1944. In addition, September 1 was the all-time wettest day on record for Newark, as well as LaGuardia Airport, New York, and the wettest September day on record for Bridgeport, Connecticut. See last paragraph for details.
- The U.S. Drought Monitor released on September 2 showed 2 percent of the Northeast in severe drought, 11 percent in moderate drought, and 11 percent as abnormally dry. Much of the Northeast saw above-normal precipitation during September, easing dry conditions in several locations. For instance, severe and moderate drought conditions eased on Cape Cod, Massachusetts, while moderate drought eased in northeastern New York and eastern West Virginia. Even in far northern New England, where drought persisted, overall coverage shrank. The U.S. Drought Monitor released on September 30 showed 1 percent of the Northeast in severe drought, 2 percent in moderate drought, and 7 percent as abnormally dry. Below-normal or lower streamflow and/or groundwater levels persisted in parts of western/southern Maine, northern New Hampshire, northern Vermont, northern New York, and Cape Cod during the month. As of late September, the number of dry wells reported in Maine was 19.
- Tropical Depression Ida trekked across the Northeast from September 1 to 3. The storm interacted with a stationary front, dropping 6 to 11 inches (152 to 279 mm) of rain on an area stretching from eastern Pennsylvania and northern/central New Jersey through the New York City metro area and into southern New England. Newark, New Jersey, saw 8.41 inches (213.61 mm) of rain on September 1, making it the site’s all-time wettest day on record and on the first day of the month already making September 2021 the site’s fourth wettest September on record. LaGuardia Airport, New York, also recorded its all-time wettest day with 6.80 inches (172.72 mm) of rain, while Bridgeport, Connecticut, which saw 5.77 inches (146.56 mm) of rain, experienced its wettest September day. Rain fell at a rate of 3 to 5 inches (76 to 127 mm) per hour in some locations, with the bulk of the daily rainfall accumulating within a six-hour period in most areas. At Central Park, New York, the 3.15 inches (80.01 mm) of rain that fell between 9 and 10 pm on September 1 was the greatest hourly amount recorded in the 132-year history of the weather station. The 2-hour and 6-hour rainfall amounts of 4.65 inches (118.11 mm) and 6.63 inches (168.40 mm), respectively, were also record setting. Newark also received record rainfall over 1-, 2-, and 6-hour durations with 3.24 inches (82.30 mm), 5.06 inches (128.52 mm), and 7.88 inches (200.15 mm), respectively. The rainfall that occurred with Ida exceeded the rainfall amounts that would be considered the 100-yr storm, having a 1 percent chance of occurring in any given year, at many locations in Pennsylvania, New Jersey, New York, and Connecticut. In fact, both Central Park and Newark saw two-hour rainfall amounts that exceeded the 500-year storm, having only a 0.2 percent chance of occurring during a given year. With saturated soils, waterways already running high, and the deluge from Ida, dozens of streamgages reached major flood stage. In fact, water levels reached historic levels at several long-term sites. For example, Brandywine Creek at Chadds Ford, Pennsylvania, which has records to the early 1900s, reached 21.04 feet (6.41 m), approaching the operational limit of the gage and beating the previous record of 17.15 feet (5.23 m) from September 17, 1999. Similarly, the Raritan River at Manville, New Jersey, which also has records back to the early 1900s, reached a new record high water level of 27.66 feet (8.43 m). Several other long-term sites reached near-record water levels. The Schuylkill River at Philadelphia, Pennsylvania, reached 16.35 feet (4.98 m), its second highest crest on record and just below the all-time highest water level of 17.0 feet (5.18 m) set on October 4, 1869. Devastating flooding occurred in multiple locations. A rare Flash Flood Emergency was declared in portions of southeastern Pennsylvania, northern/central New Jersey, and New York City. In fact, the New York National Weather Service office issued a Flash Flood Emergency for the first time ever, in northern New Jersey, then declared another one for New York City, the first time the city has been under such a warning. Numerous roads were impassable, including portions of major highways such as the Vine Street Expressway through downtown Philadelphia and FDR Drive, a major thoroughfare along the east side of New York City. Countless vehicles were stranded, including at least three school buses, and people were swept away in rising waters across the region. Public transportation around the New York City metro area ground to a halt, stranding thousands. Floodwaters poured into New York City’s subway system, with more than 800 passengers rescued, buses and above-ground trains were stranded, and lower levels of Newark International Airport took on water. Some residents were advised to shelter in place. However, in a few areas, there were concerns that dams would be overtopped, resulting in thousands of people being evacuated. Numerous structures, including homes and apartments, were inundated by floodwaters. Between flooded roads and buildings, hundreds of water rescues were performed, with the Philadelphia National Weather Service office noting that “crews are running out of resources to rescue people stuck in flood waters.” Ida also produced at least 11 tornadoes, with the most in Pennsylvania. The strongest tornado, a rare EF-3 with winds of up to 150 mph (67 m/s), carved a 12.6-mile (20.3 km) path of destruction through southern New Jersey. The tornado tossed vehicles and caused significant structural damage to dozens of homes, leaving some uninhabitable. It also destroyed barns and toppled silos at the state's largest dairy farm. Three EF-2 tornadoes, two in southeastern Pennsylvania and one in Annapolis, Maryland, caused considerable tree damage and damaged buildings and homes, tearing off roofs, blowing out exterior walls, and ripping off siding. All three tornadoes were on the ground for more than 6 miles (10 km). In addition, straight-line winds of up to 80 mph (36 m/s) caused damage in southeastern Massachusetts. Early estimates indicated the storm caused $117 million in damage in Pennsylvania and more than $50 million in damage in New York. There were at least 50 deaths due to Ida in the Northeast, including at least 13 in New York City and at least 30 in New Jersey, making it one of the state's deadliest weather events. There were a few days during the rest of September with severe weather, with storm reports noting localized flash flooding and wind damage such as downed trees and wires. For instance, straight-line winds of up to 80 mph (36 m/s) uprooted trees and flattened a corn field in central Pennsylvania on September 13. Five tornadoes touched down during the month: an EF-1 in western New York, an EF-1 in northwestern Pennsylvania, an EF-1 and EF-0 in central Pennsylvania, and an EF-0 in northern Connecticut. Hundreds of trees were damaged by the tornadoes.
- For more information, please visit the Northeast Regional Climate Center Home Page.
Midwest Region (Information provided by the Midwest Regional Climate Center)
- September temperatures were above normal across nearly all of the Midwest. The region averaged 65.7 degrees F (18.7 C) in September which was 2.1 degrees F (1.2 C) above normal. Michigan, Ohio, and Wisconsin were 1.2 to 1.7 degrees F (0.7 to 0.9 C) above normal. Illinois, Indiana, Iowa, Minnesota, and Missouri were 2.4 to 3 degrees (1.3 to 1.7 C) above normal. Only Kentucky was cooler than average for September, with average temperature 0.1 degrees F (0.1 C) below normal. There were 251 maximum high temperature records across the Midwest, with most occurring on September 14th through 21st and September 27th through 30th. Minnesota (62), Iowa (41), and Illinois (40) experienced the most record maximum high temperatures. There were 138 maximum low temperature records during the month, with double digit records broken on September 12th, 20th, and 30th. Minnesota (40), Illinois (23), and Ohio (21) saw the most maximum low temperature records.
- Precipitation amounts varied from 0.5 inches (13 mm) to 8 inches (203 mm) across the Midwest. The most abundant precipitation fell over a region extending from central Kentucky through central/eastern Indiana and western/central Ohio to southeast Michigan. Precipitation within this area ranged from 150 to 200 percent of normal. A broad corridor extending from northern Missouri to the northeast up through Iowa, Illinois, and Wisconsin had the lowest rainfall in the region, with percent of normal precipitation between 25 to 50 percent. Regionwide precipitation was 2.99 inches (76 mm), which was 0.43 inches (11 mm) below normal. Statewide precipitation totals were split above and below average across the region. The five states with below-average precipitation included Iowa (-1.73 inches (-44 mm)), Wisconsin (-1.5 inches (-38 mm)), Missouri (-1.48 inches (-38 mm)), Illinois (-0.94 (-24 mm)), and Minnesota (-0.14 inches (-4 mm)). Above average precipitation was measured for Michigan, Ohio, Kentucky, and Indiana that ranged from 0.5 to 1.15 inches (13 mm to 29 mm) above normal. There were 236 high precipitation records in September with about half of those records being set from September 21st to 23rd. Ohio (48) and Indiana (39) had the greatest number of precipitation records, occurring in the same period.
- Overall, drought conditions improved slightly throughout the majority of the region according to the U.S. Drought Monitor over the month of September. About 23 percent of the Midwest remained in D1-D3 drought and 19 percent of the region was abnormally dry (D0). In Minnesota, near normal statewide precipitation helped to eliminate all D4 (exceptional drought) from the northern reach of the state, and D3 (extreme drought) coverage declined 13 percent over the month of September. However, D2 (severe drought) remained across 50 percent of Minnesota to end the month. A small area of D3 (extreme drought) developed in late September along the border between northeast Illinois and southeast Wisconsin. D2 (severe drought) coverage expanded in central Iowa, northern Illinois, and southern Wisconsin. The greatest expansion of drought conditions occurred in Missouri, which saw abnormal dryness and moderate drought increase 45 percent during September.
- Severe weather was reported on 11 out of 30 days in September across the Midwest. While all nine states were impacted, the number of severe weather reports varied significantly across the region. Indiana, Kentucky, and Ohio each had fewer than 10 reports statewide (for all hazards) whereas Michigan and Wisconsin each recorded over 100 events. Five days recorded double digit events across the region, with one day (September 7th) recording 224 events. Hail (119) and wind (104) were the top severe weather issues on September 7th, with one tornado reported (in Illinois). Throughout September, high wind reports accounted for over half (273) of all severe weather reports across the region. Michigan (94), Minnesota (46), and Illinois (45) had the greatest number of wind events. There was a total of 173 hail events, with the most recorded in Wisconsin (82) and Michigan (37). Only seven tornados were reported, affecting just three (Minnesota, Wisconsin, and Illinois) of the nine states.
- Fire and burn restrictions that were implemented across northern Minnesota during August were scaled back during September as timely rain helped improve drought conditions. The Greenwood Fire in northeast Minnesota that had started in mid-August was 80 percent contained by late September, and all burn restrictions in that region were lifted. The greatest fire risk was isolated to the northwest portion of the state by the end of September.
- Favorable weather during September lead to corn and soybeans maturing rapidly across the region, which resulted in ahead-of-schedule harvest for the majority of the Midwest. All states except Kentucky were 5 to 13 percent ahead of schedule for corn harvest compared to the 5-year average. Corn harvest in Kentucky was 16 percent behind average at the end of September after several weeks of above average rainfall created less favorable harvest conditions. All states were at or ahead of average for soybean harvest. States in the southern Midwest were zero to seven percent ahead of soybean harvest scheduled whereas northern states were 16 to 31 percent ahead. The majority of pasture and range conditions were good to excellent for Wisconsin, Michigan, Ohio, and Kentucky. Minnesota had 51 percent of pasture and rangeland rated as being in poor to very poor condition.
- 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 near average across much of the Southeast region for the month of September. Monthly mean temperatures were within 2 degrees F (1.1 degrees C) of normal for over 94 percent of the 154 long-term (i.e., period of record equaling or exceeding 50 years) stations across the region. There were only a handful of stations that observed monthly mean temperatures that were ranked within their ten warmest values on record, including San Juan, PR (1898-2021; 1st warmest) and Orlando, FL (1892-2021; 6th warmest). Maximum temperatures ranged from 3.7 degrees F (2.1 degrees C) above normal in Lynchburg, VA (1893-2021) to 3.9 degrees F (2.2 degrees C) below normal in Huntsville, AL (1894-2021). Daily temperature minimums ranged from 3.2 degrees F (1.8 degrees C) above normal in Clayton, NC (1955-2021) to 3 degrees F (1.7 degrees C) below normal in Andrews, SC (1962-2021). With warmer-than-normal sea surface temperatures measured offshore, a few stations along the coastline of Florida and Puerto Rico observed minimum temperatures equal to or above 70 degrees F (21 degrees C) for the entire month including, West Palm Beach, FL (1888-2021), Fort Myers, FL (1902-2021) and San Juan, PR (1898-2021). The warmest weather of the month occurred from the 12th through the 14th, as a warm and humid air mass stagnated over the region. Daily maximum temperatures exceeded 90 degrees F (32 degrees C) across portions of every state, while nighttime minimum temperatures remained above 60 degrees F (15.6 degrees C). In contrast, the coldest weather of the month across the Southeast occurred on the 24th through the 26th, as the circulation around a departing mid-latitude cyclone ushered in relatively cooler and drier air from Canada. Daily minimum temperatures fell below 60 degrees F (16 degrees C) across portions of every state including Florida, with some locations in the higher elevations of North Carolina and Virginia falling below 40 degrees F (4.4 degrees C).
- Precipitation varied across the region for September, with the driest locations found across much of North Carolina, South Carolina, eastern Virginia, and Puerto Rico. Monthly precipitation totals ranged from 70 to less than 25 percent of normal across these locations. Indeed, Greenville, NC (1875-2021; 10th driest September) only measured 1.31 inches (33 mm) of precipitation, which was more than 6 inches (152 mm) below average. In contrast, Wilmington, NC (1871-2021) observed 10.77 inches (274 mm) of rainfall this month, 2.08 inches (53 mm) above average; however, most of that fell on the 21st and 22nd, as thunderstorms associated with a stalled frontal boundary dropped over 8 inches (203 mm). The wettest locations for the month were located across western Virginia, central Georgia, and parts of Alabama. Precipitation totals ranged from 150 to 200 percent of normal. Savannah, GA (1871-2021; 18th wettest) measured 9.52 inches (242 mm) of precipitation, over 5 inches (127 mm) above normal, and Columbus, GA (1891-2021) observed its 6th wettest September with 6.18 inches (157 mm) for the month. On the first of the month the remnants of Hurricane Ida went through the Washington D.C. area, causing heavy rainfall and much localized flooding. Several road closures and a few water rescues were also reported. On September 7th a line of thunderstorms produced 8.17 inches (208 mm) of rain in Cobb County, GA, with rainfall rates of over 3 inches (76 mm) per hour, prompting many alerts for flash flooding. Tropical Storm Mindy made landfall in St. Vincent Island, FL on September 8th, dropping between 2 to 4 inches (51 to 102 mm) of precipitation across northern Florida and southern Georgia before quickly tracking to the northeast. The storm, however, caused minimal damage. Thunderstorms on the 20th produced 6.66 inches (169 mm) of rainfall in Savannah, GA (1871-2021), making this the 4th wettest September day on record. Likewise, on the 22nd, thunderstorms dropped 4.44 inches (113 mm) in Blacksburg, VA (1893-2021), making this its 2nd wettest day on record.
- There were 44 reports of severe weather across the Southeast during September, which is 44 percent of the median monthly frequency of 100 reports during 2000-2019. There were no confirmed tornadoes reported for the month, which is 15 below the monthly average. There was, however, a brief waterspout on September 13th spotted just offshore of Fort Lauderdale Beach, FL. No injuries were reported. There were 4 reports of hail for the month, with the largest being golf-ball sized (1.75 inches) in Albemarle County, VA on the 28th. There were 39 wind reports for the month, which is 51 percent of the average (77 reports). Thunderstorms produced wind gusts of 58 mph (26 m/s) in Brevard County, FL at the NASA shuttle landing facility on the 2nd. No damage was reported. Strong winds, associated with thunderstorms along a cold front, gusted to 60 mph (27 m/s) in Chatham County, NC on September 22nd. Several tree branches were downed, but no injuries were reported. There were four people struck by lightning during the month; a 19 year old man was killed on September 7th in Lakewood Ranch, FL, and 3 men were injured by lightning while working on a roof in Durham, NC on the 8th. Unfortunately, there were 6 rip current deaths for the month; 2 in Destin, FL, 2 people in Sunnyside, FL, and 2 in Daytona Beach, FL.
- Drought conditions improved slightly across the Southeast region for September. Adequate precipitation eliminated the small pocket of moderate drought (D1) in western Virginia. Only a few pockets of abnormally dry conditions (D0) remain in Virginia and North Carolina. Drought remained mostly the same across Puerto Rico, with an area of moderate drought (D1) in the southern part of the island and a few pockets in the northern part, ringed by areas of abnormally dry conditions (D0). The citrus growing region in Florida experienced a decrease in precipitation by the end of the month forcing farmers to irrigate in several areas. Rains during the beginning of the month in the Florida Panhandle caused disease pressure on field crops and increased leaf spot in peanuts. The dry weather towards the end of the month, however, benefitted many crops and a variety of fruits and vegetables were planted and marketed. Similarly, in Georgia, producers were able to harvest corn and cut hay during the drier end of the month. Boll rot in cotton was noted due to the wet conditions during the beginning of the month. Leaf spot and white mold were noted by peanut farmers. Farmers also experienced negative effects on pastures and hayfields from armyworms and bermudagrass stem maggots. Pasture conditions in South Carolina, however, benefitted greatly from adequate soil moisture and moderate temperatures.
- For more information, please visit the Southeast Regional Climate Center Home Page.
High Plains Region (Information provided by the High Plains Regional Climate Center)
- Temperatures remained slightly above normal across the region for September aside from a small area in western Wyoming that observed below normal temperatures. The highest departures from normal were observed in North Dakota, Kansas, western South Dakota and Nebraska, and eastern Wyoming and Colorado. These areas observed temperatures over 4.0 degrees F (2.2 degrees C) above normal for September. As a result of these above-normal temperatures, many locations ranked in the top 5 warmest September on record. Chadron, NE tied a previous record set in 1969 for the warmest September on record with an average temperature of 67.0 degrees F (19.4 degrees C) which was 4.2 degrees F (2.3 degrees C) above normal. Five other locations in Nebraska, North Dakota, and Colorado, observed the 2nd warmest September on record (see page 6 for monthly rankings). Warm temperatures in the region at the end of the month resulted in many areas in North Dakota surpassing daily temperatures records, including Dickinson, ND with a record of 100.0 degrees F (37.8 degrees C) on the 28th of September surpassing a record of 98.0 degrees F (36.7 degrees C) set in 1905. This also is the latest in the year any station in North Dakota has reached 100.0 degrees F (37.8 degrees C) or higher. Bismarck, ND also reached its 50th day this year with a high temperature equal to or above 90.0 degrees F (32.2 degrees C), the record being 53 days set in 1936. Despite these high temperatures, some minor improvements were seen in drought conditions throughout September in North Dakota and other areas within the region.
- Precipitation varied for September but remained at or near normal across most of the region. With precipitation near-normal, only a few areas ranked in the top 10 wettest or driest on record for September (see page 6 for monthly rankings). Portions of eastern South Dakota, central Nebraska, and Kansas received the greatest departure from normal with total precipitation as much as 2 to 3 inches (50.80 to 76.20 mm) above normal for the month. Valentine, NE observed 4.01 inches (101.85 mm) for the month ranking it the 5th wettest September on record, with the wettest being 5.91 inches (150.11 mm) set in 1973. This was also 233 percent above normal for the month. The above normal precipitation across central Nebraska slowed corn harvest ending the month with 21 percent of the corn being harvested. Corn harvest, which has been impacted due to the drought, began early harvest this year in September. However, this much needed precipitation across the region did help to provide some minor improvements to drought conditions, most of which was observed in South Dakota, and helped return streamflow in most of the region to normal and above normal. In contrast to the above normal precipitation, portions of Wyoming and North Dakota observed slightly below normal precipitation and ranked in the top 10 driest for the month. Sheridan, WY, which received 13 percent of normal precipitation, ranked the 2nd driest September on record with a total on 0.04 inches (1.02 mm) of precipitation (the driest record being a trace recorded in 2012). Williston, ND also ranked in the top 10. Williston observed 0.10 inches (2.54 mm) for September ranking it as the 7th driest on record (the driest record being 0.01 inches, 0.25mm, recorded in 1899). This lack of precipitation has impacted wetlands in North Dakota. As a result, North Dakota’s duck hunters are observing poor wetland conditions which will impact the duck hunting season. The number of duck hunting wetlands are down 44 percent across the state from last fall as a result of the lack of precipitation and drought conditions.
- Much needed precipitation in some portions of the region has helped to provide minor relief to drought conditions and restored streamflow. Precipitation in areas of South Dakota, Nebraska, and Kansas were as much as 150 percent above normal for the month. South Dakota, which began the month with 64.69 percent of the state in D3-D4 drought conditions, has observed small improvements and ended the month with 58.62 percent in D3-D4 drought conditions. Despite these improvements, the scope of the drought has been so extreme that it will continue to take a notable amount of precipitation to see any relief in these regions. It is observed that precipitation aided in streamflow conditions in the eastern portion of the region. Streamflow across the Dakotas and lower basin returned to normal and some even observed much above normal streamflow. Cooler temperatures also helped in bringing relief across part of the region. Firefighters took advantage of the cooler temperatures in September and were able to expand containment of the Crater Ridge Fire in Wyoming from 35 to 52 percent. As a result, air quality across the state has improved compared to earlier in the summer. While these fires continue to be a concern in Wyoming, wildland fire potential will begin to decrease throughout October and return to normal in November. Higher elevations in Wyoming and Colorado observed their first snow for the season in September. A dusting was observed in Northwest Colorado near Rabbit Ears Pass and Cameron Pass. Light snow was also observed in Rocky Mountain National Park and even resulted in road closures due to whiteout conditions from blowing snow. In Wyoming, a light blanket of snow was observed in Grand Teton and Yellowstone National Park. While neither were measurable events, cooler temperatures are on the way as we continue into fall.
Southern Region (Information provided by the Southern Regional Climate Center)
Hurricane Nicholas made landfall in Texas, but western parts of the Southern Region became drier overall.
- September 2021 was a relatively hot month for Oklahoma and Texas, while states farther east were relatively mild. The Oklahoma and Texas average temperatures were 76.6 °F (24.8 °C) and 78.3 °F (25.7 °C), respectively, ranking 13th and 14th warmest all-time. Meanwhile, Arkansas was only 45th warmest, and Tennessee (59th coolest), Louisiana (53rd coolest), and Mississippi (62nd coolest) all averaged below-median out of 127 years of data. The region-wide average was 76.5 °F (24.7 °C), 28th warmest on record. No record high monthly temperatures were set across the region. Hottest was 109 °F (43 °C) at Rio Grande Village, TX, on September 21, while coldest was 28 °F (-2 °C) at Mt. Leconte, TN, on September 24, the only station in the entire region to experience below-freezing temperatures.
- Both Texas and Oklahoma endured very dry Septembers, while above-normal rainfall generally continued for states farther east. Average precipitation in Oklahoma was 1.14” (29 mm), the 9th driest September historically. Texas was marginally wetter, at 1.24” (31 mm), 11th driest historically, and Arkansas was also relatively dry, with 1.99” (51 mm) placing it 28th wettest overall. During the same month, Louisiana was 15th wettest (6.58”, or 167 mm), Tennessee was 22nd wettest (4.75”, or 121 mm), and Mississippi was 33rd wettest (4.33”, or 110 mm). Two long-term stations had their wettest September day on record: Bunkie, LA, at 10.60” (269 mm) on September 15, associated with the remnants of Hurricane Nicholas, and Tullahoma, TN, at 4.65” (118 mm) on September 19. Bunkie’s monthly total was 19.09” (485 mm), the largest reliable rainfall total for the month. In Texas and Oklahoma, though, fifteen stations reported zero precipitation and another sixteen reported just a trace.
- Update: Last month we reported that Louisiana had received at least 5.63” (143 mm) of rain during August, but that the actual total was probably higher because many stations in the path of Hurricane Ida were missing. With some of the missing data now in, Louisiana’s August total now stands at 5.98” (152 mm), or 31st wettest on record.
- The lack of rainfall in Texas and Oklahoma followed a mostly dry August. Thus, drought spread rapidly across western portions of the Southern Region. On August 31, only 1.3% of the region was in drought. One month later, on September 28, 13.9% of the region was in drought and another 31.2% of the region was abnormally dry. Oklahoma was hardest hit, with 73.2% of the state in at least moderate drought on September 28, 23.7% in severe drought, and 2.7% in extreme drought. On August 31, only 6.6% of Oklahoma had at least moderate drought and only 0.7% of the state was in severe drought. This was the most rapid drought development in Oklahoma since the summer of 2012. Ranchers reported needed supplemental feedings for the cattle, and stock tanks were very low in some areas.
- Hurricane Nicholas
- Tropical Storm Nicholas formed over the Bay of Campeche on September 12 and drifted northward. At 10:00 PM CDT, the National Hurricane Center upgraded Nicholas to a hurricane, and it made landfall a couple of hours later on the Matagorda Peninsula along the Texas coast. Nicholas produced a fairly standard mix of minimal hurricane impacts. A few feet of storm surge affected areas around Freeport and Galveston Bay, power was knocked out to about half a million customers, and heavy rainfall caused localized flooding. Nicholas continued moving northeastward after landfall, eventually stalling over Louisiana and contributing to widespread and intense rainfall over much of southern Louisiana and southern Mississippi.
- Severe Weather
- There was one confirmed tornado or set of tornadoes, just west of Hammon, Oklahoma, on September 7. All of the damage was rated EF0 on the Enhanced Fujita Scale. Hail of 1” (2.5 cm) diameter or greater was reported at 14 locations, most of them Oklahoma and Texas on September 29 and 30. The strongest estimated wind was 86 mph near Rosston, Oklahoma, downing some power lines in the area.
- For more information, please visit the Southern Regional Climate Center Home Page.
Western Region (Information provided by the Western Region Climate Center)
- Often marking a transitional month into the boreal cool season, September 2021 brought flat ridging with slightly above normal geopotential heights over much of the western US. A deeper-than-normal (i.e., stronger) Aleutian low was a notable regional circulation anomaly for the month. These conditions led to generally seasonable, but slightly warmer than usual, temperatures across the West. An early season extratropical cyclone associated with an atmospheric river impacted the Pacific Northwest bringing welcome and much-needed precipitation. Monsoonal precipitation continued in southern Arizona and western New Mexico. Otherwise extremely dry conditions persisted across California, Nevada, Idaho, Utah, and Montana. These dry conditions allowed wildfire activity to continue in the west, especially in the Sierra Nevada of California, with ongoing impacts to regional and local air quality. Drought conditions persisted and worsened in Hawaii while Alaska received uncharacteristic heavy snowfall.
- Temperatures in the majority of the West were near-to-slightly above-average during September, with slightly above normal (0–3°F; 0–1.6°C) temperatures. Increased cloud cover and cold air associated with the passage of early season frontal storms brought slightly below average (0-3°F; 0–1.6°C) temperatures to the Pacific Northwest. Continued monsoonal activity helped keep parts of the Desert Southwest cool. At 2.3°F (1.3°C) cooler than its average of 72.8°F (22.7°C), San Simon, AZ tied its 10th coldest September since 1898. Hot conditions continued in Davis, CA, which observed its warmest September in 116 years with an average of 76.7°F (24.8°C), which is 4.4°F (2.4°C) above average. With records beginning in 1948, September was tied the 5th warmest at Glasgow, MT with an average temperature of 63.6°F (17.5°C) or 3.7°F (2°C) above normal.
- Precipitation in the West was varied during September and ranged from above average to record dry. Oregon, and Washington benefitted from early season rainfall while many regions continued to observe dry conditions. Recording 9.7 in (246 mm) of rainfall, Quillayute, WA recorded its fourth-wettest September in 56 years of observations (215% of normal). Astoria, OR observed 5 in (127 mm) of precipitation, making September its 8th wettest (187% of normal) since record keeping began in 1953. In the Desert Southwest, September typically marks the termination of the North American Monsoon. September 2021 continued the theme of an active monsoon season. With 1.95 in of rainfall, San Simon, AZ experienced its 9th wettest (215% of normal) September since 1898. Since observations began in 1880 at Butte, MT, September 2021 tied its fourth driest September on record with 0.07 in (1.8 mm) of precipitation (6% of normal). In Fresno, CA, where record keeping started in 1880, recorded 0 in (0 mm) of rainfall, tying its driest September on record (0% of normal).
- Sea surface temperatures (SST) in the vicinity the Hawaiian Islands were slightly below average (0–1.5°F; 0–0.8°C). Temperatures on the Hawaiian Islands in September were generally near-normal. Recording 0.12 in (3 mm) of rainfall (13% of average), Honolulu tied its 11th driest September since record keeping began in 1940. As a result of the dry conditions, drought persisted on all islands with no improvement from the month prior according to the US Drought Monitor. Maui is experiencing the most severe drought conditions. All parts of Lānaʻi, Kahoʻolawe, Molokaʻi, and Niʻihau are in some level of drought, with extreme drought now also occurring on Lānaʻi and Molokaʻi.
- September continued the trend of slightly cooler temperatures in Alaska and is typically the month during which temperatures rapidly cool. Many regions were warmer than normal during the start of the month but notably colder than normal during the end of the month. In the southwest, with an average temperature of 43.2°F (6.2°C) King Salmon observed its second coldest September on record (5.5°F (3°C) below normal). Southeast Alaska was wetter than usual. A grand total of 23.6 in (599 mm) of precipitation was measured at Ketchikan (165% of normal), leading to the seventh wettest September since 1910. September also brought early season snowfall to many regions across the state. Tok observed 16 in (40 cm) of snow, making for the snowiest September in 55 years. The Chugach mountains around Anchorage received 15-25” (38-64 cm) of snow. This is the most snowfall observed since observations at higher elevations began in the late 1970s. Curiously, only a trace of snowfall was observed in the western margin of Anchorage. Likely favored by enhanced cloudiness associated with lower pressure than normal, Chukchi Sea ice extent was the highest since 2006.
- Significant Events for September 2021
- Early season landfalling atmospheric river in the Pacific Northwest: A strong landfalling atmospheric river event on September 16-19 brought upwards of 5 in (250 mm) of precipitation to the mountains of the Olympic Peninsula and the North Cascades with 2-3 in (50-75 mm) in other mountain regions. 1-2 in (25-50 mm) was recorded in lower elevation regions. With numerous large wildfires ongoing throughout the region, this precipitation helped raise fuel moistures and decrease fire activity. These effects reduced smoke output from ongoing fires leading to improved air quality across the region and in areas downstream. The strongly orographic precipitation pattern produced notable precipitation gradients, with leeside regions receiving substantially less precipitation (0-0.5 in; 0-13 mm) than windward regions.