National Overview - May 2013
NCDC added Alaska climate divisions to its nClimDiv dataset on Friday, March 6, 2015, coincident with the release of the February 2015 monthly monitoring report. For more information on this data, please visit the Alaska Climate Divisions FAQ.
Maps and Graphics
Temperature and Precipitation Ranks
U.S. Percentage Areas
Supplemental May 2013 Information
- Year-to-date temperature evolution for select U.S. cities
- Spring daily temperatures compared to normal
- Locations with more snowfall in spring, compared to winter
- May EF-5 tornado information and visualization
- May daily temperature extremes
- Climate Highlights — May
- The May average temperature for the contiguous U.S. was 61.0°F, which was 0.9°F above the 20th century average. May ranked as the 40th warmest such month on record.
- The southeastern U.S. was cooler than average, while the rest of the nation had near and above-average May temperatures. Florida had its 11th coolest May, and Georgia had its 12th coolest, with monthly temperatures 1.5°F and 2.6°F below average, respectively.
- May precipitation, averaged across the contiguous U.S., was 3.34 inches, 0.47 inches above average, and the 17th wettest May on record. It was also the wettest May since 1995.
- Most of the northern U.S. had above-average May precipitation. Iowa had its wettest May on record with 8.84 inches of precipitation, 4.77 inches above average. Montana and North Dakota each had one of their top ten wettest Mays. The above-average precipitation contributed to flooding along several major rivers in the region including the Mississippi River and the Illinois River.
- According to the June 4 U.S. Drought Monitor Report, 44.1 percent of the contiguous U.S. was experiencing moderate-to-exceptional drought, smaller than the 46.9 percent at the beginning of May. Drought continued to improve for parts of the Great Plains, but worsened in the West. Several months of warm and dry conditions in California led to nearly the entire state being in drought by early June.
- Despite a below-average preliminary tornado count during May for the contiguous U.S., several large and powerful tornadoes hit populated areas resulting in significant damage and loss of life. Two EF-5 tornadoes, the highest strength rating given to a tornado, were confirmed near Oklahoma City. The EF-5 tornado that hit Moore, Oklahoma, on May 20th destroyed thousands of homes and businesses in and around the city and was blamed for over 20 fatalities. According to preliminary analysis, the EF-5 near El Reno, Oklahoma, on May 31st had a path width of approximately 2.6 miles, the widest tornado ever observed in the United States. These two events were only the 7th and 8th EF-5 tornadoes confirmed in Oklahoma in the 64-year period of record.
- Several late-season winter storms impacted the U.S. during May, bringing snowfall to the Central and Northern Plains, as well as the Northeast, while below-average snow cover continued for the West. According to data from the Rutgers Global Snow Lab, the May snow cover extent of 6,564 square miles was 56,757 square miles below the 1981-2010 average, and the second smallest May snow cover extent on record.
- Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand ranked as the 7th lowest May value in the 119-year period of record.
- Climate Highlights — spring (March — May)
- The spring average temperature for the contiguous U.S. was 50.5°F, 0.5°F below the 20th century average, making it the 38th coolest spring on record and the coolest spring since 1996.
- Spring 2013 marked the first season in the contiguous U.S. that the seasonal temperature was not above average since the winter of 2010-2011, when the seasonal temperature was 0.8°F below average.
- Spring was cooler than average for a large portion of the contiguous United States, east of the Rockies. Fourteen states, from North Dakota to Georgia, had spring temperatures that ranked among the ten coldest.
- New England and the West were both warmer than average. California had its seventh warmest spring on record with a seasonal temperature 3.5°F above average.
- The spring precipitation total for the nation of 7.92 inches was 0.21 inch above average. The nationally-average precipitation total masked regional wet and dry extremes during the season.
- Iowa had its wettest spring on record with 17.61 inches of precipitation, 8.63 inches above the seasonal average. Wetter-than-average conditions were observed in the Northern Plains and Midwest, where North Dakota, Minnesota, Wisconsin, Illinois, and Michigan each had one of their top ten wettest spring seasons.
- Below-average precipitation was observed in the Mid-Atlantic, Southern Plains, and West. New Mexico had its second driest spring with 0.66 inches of precipitation, 1.72 inches below average. California had its eighth driest spring, with 2.34 inches of precipitation, 3.33 inches below average.
- The above-average precipitation and below-average temperatures in the north-central United States were associated with a spring snow cover extent that was above average. According to data from the Rutgers Global Snow Lab, the spring snow cover extent was the eighth largest on record and the largest since 1984.
- The U.S. Climate Extremes Index (USCEI), an index that tracks the highest and lowest 10 percent of extremes in temperature, precipitation and drought across the contiguous U.S., was 140 percent of average during spring. The above-average USCEI was driven by extremes in below-average temperatures, extremes in 1-day precipitation totals, and the spatial extent of drought.
- Climate Highlights — year-to-date (January — May)
- The year-to-date national temperature of 43.6°F was 0.2°F above the 20th century average. Below-average temperatures were observed for much of the central United States, from Rockies to the Mid-Atlantic. The Northeast and parts of the West had above-average year-to-date temperatures.
- The January-May precipitation total for the contiguous U.S. was 12.28 inches, 0.33 inch above average. North Dakota, Minnesota, Wisconsin, Missouri, and Mississippi each had a top ten wet 5-month period; Iowa, Illinois, and Michigan were record wet during January-May.
- The West, Southern Plains, and Northeast were drier than average. Oregon, Nevada, Idaho each had a top ten dry year-to-date period, while California had its driest January-May on record with 4.09 inches of precipitation, 9.87 inches below average.
- During both the year-to-date and 3-month timescales, the number of fires, acreage burned, and acres burned per fire were record low.
- The USCEI for the year-to-date period was near average. However, several of the components were above average. The component for extremes in 1-day precipitation totals was 200 percent of average and the highest value on record for the 5-month period, while the component that examines the spatial extent of drought was 270 percent of average and the ninth highest
Alaska Temperature and Precipitation:
- Alaska had its 20th coolest May since records began in 1918, with a temperature 2.3°F (1.3°C) below the 1971–2000 average.
- Alaska had its 18th coolest March-May since records began in 1918, with a temperature 3.2°F (1.8°C) below the 1971–2000 average.
- Alaska had its 40th warmest January-May since records began in 1918, with a temperature near the 1971–2000 average.
- Alaska had its 14th wettest May since records began in 1918, with an anomaly that was 25.1 percent above the 1971–2000 average.
- Alaska had its 31st wettest March-May since records began in 1918, with an anomaly that was 17.0 percent above the 1971–2000 average.
- Alaska had its 14th wettest January-May since records began in 1918, with an anomaly that was 29.2 percent above the 1971–2000 average.
For additional details about recent temperatures and precipitation across the U.S., see the Regional Highlights section below and visit the Climate Summary page". For information on local temperature and precipitation records during the month, please visit NCDC's Records 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 Climatic Data Center.
- Northeast Region: (Information provided by the Northeast Regional Climate Center)
- With an average temperature of 57.7 degrees F (14.3 degrees C), the Northeast was 1.3 degrees F (0.7 degrees C) above normal for May. New Jersey was the lone cool state at -0.1 degrees F (-0.1 degrees C). Departures for the rest of the states ranged from +0.1 degrees F (+0.1 degrees C) in Maryland to +2.4 degrees F (+1.3 degrees C) in Vermont. As for spring, the Northeast was slightly above normal. The average temperature of 45.8 degrees F (7.7 degrees C) was 0.1 degrees F (0.1 degrees C) above average. Seven states ended the season cooler than normal. Departures for those states ranged from -1.3 degrees F (-0.7 degrees C) in West Virginia and Maryland to -0.1 degrees F (-0.1 degrees C) in New York. For the five warm states, departures ranged from +0.1 degrees F (+0.1 degrees C) in Rhode Island to +1.6 degrees F (+0.9 degrees C) in Maine.
- After four dry months in a row, the Northeast was slightly wetter than normal in May. The region received 4.09 inches (103.89 mm) of precipitation, 102 percent of normal. The states were split with six wetter than normal and six drier. Both Maine (149 percent of normal) and Vermont (140 percent of normal) ranked this May as their 12th wettest since 1895. New Hampshire, with 123 percent of normal, ranked the month as their 17th wettest May while Massachusetts, with 119 percent of normal, ranked it as their 20th wettest. New York's departure was 108 percent of normal and Connecticut's was 102 percent of normal. For the dry states departures ranged from 64 percent of normal in Delaware to 94 percent of normal in Rhode Island and New Jersey. Receiving 9.24 inches (234.70 mm), 83 percent of normal, the Northeast was below normal for spring precipitation. Despite a wet May in some states, all states ended spring drier than normal. Rhode Island was the driest state at 59 percent of normal, making it their 17th driest spring in 119 years. Connecticut, with 62 percent of normal precipitation, had their 20th driest spring on record. Departures for the rest of the states ranged from 74 percent of normal in Pennsylvania to 99 percent of normal in Vermont.
- At the beginning of May a continuing lack of precipitation caused most of New England to be under abnormally dry (D0) or moderate drought (D1) conditions according to the U.S. Drought Monitor. Rains during the second half of the month helped ease dryness, but areas of D0 and D1 remained. Though D1 conditions eased, abnormal dryness lingered in parts of New York. At the start of the month around two-thirds of Pennsylvania was abnormally dry, but improving conditions lowered that to one-fourth by month's end. Despite improvement in other parts of Pennsylvania, conditions deteriorated to D1 in the southwest corner. Much of West Virginia was under abnormally dry or moderate drought conditions at the start of the month and although conditions improved slightly, areas of D0 and D1 remained. In New Jersey and western Maryland, dry conditions were eased.
- Severe storms throughout May produced eight tornadoes in the Northeast: an EF-0 in Massachusetts on the 9th; three EF-1s and an EF-0 in Pennsylvania on the 28th; and two EF-1s and a mile-wide (1.6 km) EF-2 in New York on the 29th. The Pennsylvania tornadoes downed hundreds of trees while the EF-2 tornado in New York tore roofs off buildings and toppled high-tension power line towers. Several funnel clouds were also spotted throughout the month. Additionally, severe storms produced damaging straight-line winds, hail up to 2.5 inches (6.4 cm) in diameter, and flash flooding. One of the hardest hit areas for flash flooding was Chittenden County, Vermont, which received up to 7 inches (177.8 mm) of rain during the week of the 19th through the 24th. Flash flooding washed out roads and culverts, damaged bridges, and caused road closures. Located on the border of the county, Mount Mansfield set a record (and tied the New England record) for most consecutive days with an inch (2.5 cm) of precipitation with five such days from the 22nd through the 26th. Also located in Chittenden County, Burlington set a new precipitation record for May with 8.74 inches (222 mm). The old record was 8.67 inches set in 2011. Cold air behind the flood-inducing system allowed some higher elevations of New York, Vermont, and New Hampshire to see snow the weekend before Memorial Day. Mount Mansfield accrued 13.2 inches (33.5 cm) from the 25th to the 26th, making it the latest in the season that the peak has received a foot (30.5 cm) of snow, while Whiteface Mountain in upstate New York accumulated 36 inches (91.4 cm) at its peak.
- For more information, please go to the Northeast Regional Climate Center Home Page.
- Midwest Region: (Information provided by the Midwest Regional Climate Center)
- May temperatures were generally above normal in eastern parts of the Midwest and below normal in western parts. Temperatures ranged from 3 degrees F (1.7 degrees C) below normal in central Minnesota to 4 degrees F (2.2 degrees C) above normal in parts of Michigan and Ohio. Daily temperature records alternated between record highs and record lows as weather moved across the region during the month. The warmer temperatures in the east brought spring (March to May) temperatures close to normal while the cool temperatures in the west continued the cool spring pattern. Spring temperatures ranged from near normal in the east to 8 degrees F (4.4 degrees C) below normal in west central Minnesota.
- May precipitation also varied across the Midwest in May. Like temperature, precipitation varied from west to east with wet weather in the west and dry conditions in the east. A large area that included parts of Missouri, Illinois, Iowa, Minnesota, and Wisconsin had more than 7 inches (178 mm) of precipitation and totals exceeded 15 inches (381 mm) at some stations in central Iowa. Using data that extends back to 1895, Iowa set a new statewide precipitation record for both the month and the spring season. The wet weather in the western half of the Midwest for the year-to-date (January to May) ranked statewide values as the wettest on record not only in Iowa, but also in Illinois and Michigan. Three other states (Minnesota, Missouri, and Wisconsin) ranked in the top 10 wettest for January to May.
- Snow fell in the first week of May and was unusually heavy with many daily and monthly records set. The snow extended from southwest Missouri to the southwest shore of Lake Superior and totals ranged up to 5 inches (2.0 cm) in Missouri, over a foot (30.5 cm) in Iowa, and over 17 inches (43.2 cm) in parts of southeast Minnesota and western Wisconsin. Daily records topped 225 for the month with dozens on the 2nd and 3rd while records for any day in May were only slightly lower with 160 records and again dozens on both the 2nd and the 3rd.
- The cool spring weather had suppressed severe weather in the region through April but that all changed in May. An active weather pattern which brought sufficient warmth to support strong thunderstorms contributed to a big increase in severe weather reports in May. Iowa had multiple tornadoes on the 19th which were the first reported in the state since May 24, 2012. The string of 359 days without a tornado in the state was a record for the period from 1950 onwards. Tornadoes also touched down in Minnesota, Wisconsin, Michigan, Missouri, Illinois, and Indiana. Hail and wind damage reports were widespread across the region.
- May rains continued to erode away the remaining drought areas in the Midwest. By the end of the month, the area of the Midwest in drought dropped to less than 4 percent and severe drought area fell below 1 percent. The heavy rains in 2013 have restored much of the soil moisture, stream flow, and small lake level deficits from 2012. River levels on the Mississippi River went from near record low levels in January to major flooding in May. Major flooding affected numerous river systems in the western half of the region from Missouri to western Michigan and areas to the west.
- For details on the weather and climate events of the Midwest, see the weekly summaries in the Midwest Climate Watch page.
- Southeast Region: (Information provided by the Southeast Regional Climate Center)
- Mean temperatures in May were below average across much of the Southeast region. The greatest departures were found across parts of Alabama, Georgia, South Carolina, and northeastern Florida, where monthly temperatures were 2 to 3 degrees F (1.1 to 1.6 degrees C) below average. Jacksonville, FL recorded its 3rd coldest May in a record extending back to 1871. Temperatures across the rest of the region were 1 to 2 degrees F (0.5 to 1.1 degrees C) below average, except across eastern portions of Virginia and North Carolina, where monthly temperatures were as much as 2 degrees F (1.1 degrees C) above average. Monthly temperatures were also above average across Puerto Rico, while temperatures were generally below average across the U.S. Virgin Islands. Several rounds of unseasonably cool weather affected the Southeast in May, resulting in nearly 300 daily minimum temperature records and over 250 daily low maximum temperature records tied or broken across the region. Many of these records occurred from the 13th to the 15th of the month. During this period, subfreezing temperatures were recorded across northern Virginia and along the higher elevations of the Southern Appalachians, including a minimum temperature of 25 degrees F (-3.9 degrees C) at the summit of Mount Mitchell, NC on the 13th and 14th. The warmest weather of the month occurred days later on the 16th and 17th as temperatures exceeded 90 degrees F (32.2 degrees C) across parts of Virginia and the Carolinas. More daily minimum temperature records were tied or broken on the 25th of the month, including 41 degrees F (5 degrees C) at Raleigh-Durham, NC, 43 degrees F (6.1 degrees C) at Charlotte, NC, and 48 degrees F (8.9 degrees C) at Wilmington, NC. May marked the end of an exceptionally cold meteorological spring (March-May) at several locations across the Southeast, including Jacksonville, FL (2nd coldest), Augusta, GA (3rd coldest), Gainesville, FL (4th coldest), and Mobile, AL (tied for 5th coldest).
- Monthly precipitation totals were above normal across a large portion of the Southeast in May. The wettest locations were found across southern and northeastern Florida, as well as northern sections of Alabama, Georgia, and South Carolina, western sections of North Carolina, and the northern shores of Puerto Rico, where monthly precipitation totals were as much as 300 percent of normal. San Juan, PR recorded its 3rd wettest May with 14.54 inches (369.3 mm) of rain (period of record: 1898-2013), while West Palm Beach, FL and Miami, FL recorded 15.67 and 11 inches (398.1 and 279.4 mm) of rain, respectively. Much of the precipitation in Northeast Florida fell between the 3rd and 5th of the month, as strong storms dropped as much as 9 inches (228.6 mm) of rain in the St. Augustine area. Widespread rain fell from Alabama to Virginia as a slow-moving weather system tracked across the region from the 3rd to the 9th of the month. Daily rainfall totals during this period exceeded 5 inches (127 mm) locally across parts of northern Alabama, Georgia, and western North Carolina. A mudslide in McDowell County, NC on the 5th of the month claimed the life of a Norfolk Southern worker who was inspecting a rail line near Black Mountain. Another period of wet weather occurred from the 17th to the 24th of the month. Between 3 and 5 inches (76.2 and 127 mm) of rain fell locally across the Florida Peninsula, Alabama, Georgia, and the Carolinas, while as much as 8 inches (203.2 mm) of rain fell across parts of south Florida. Strong storms with rainfall rates exceeding 2 inches (50.8 mm) per hour resulted in flash flooding in Key West, FL on the 2nd of the month and again on the 29th of the month. In contrast, May was a relatively dry month across the western Panhandle of Florida, southern sections of Alabama and Georgia, and eastern North Carolina, where monthly precipitation totals were less than 50 percent of normal.
- There were 194 reports of severe weather across the Southeast in May, with at least one report on 19 of the 31 days. A total of four EF-0 tornadoes were confirmed across the region. Two of these occurred along the east coast of Florida, one near Boca Raton on the 2nd of the month and one in the town of Elkton (outside of Jacksonville) on the 4th of the month. The other two confirmed tornadoes occurred in northern Alabama in the towns of Athens and Elkmont (near Huntsville) on the 17th of the month. The damage from these storms was mostly minor and involved only a few homes and outbuildings, although one home in the Athens area did experience some structural damage. On the 28th of the month, a woman was killed after being struck by lightning on Belleair Beach near Clearwater, FL.
- Only minor changes in the Drought Monitor were noted across the Southeast in May. Areas of moderate (D1) and severe (D2) drought were reduced slightly across north-central Florida, while abnormally dry conditions (D0) were eliminated across South Carolina, marking the first time the state has been drought-free since April 2010. Abnormally dry conditions continued to persist across eastern North Carolina, while areas of moderate drought re-emerged across extreme northwest Florida and southern Alabama. Although conditions in these areas continued to limit forage growth, the dry weather and soils aided in the planting and harvesting of many summer crops. Saturated soils combined with cool spring temperatures delayed the planting and harvesting of crops across much of North Carolina and Virginia. The most significant agricultural impacts were noted across western North Carolina, where heavy rains flooded fields and washed away crops. The cool, wet conditions in May were also associated with a complete absence of ground-level ozone violations in the Atlanta, GA metropolitan area.
- 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)
- May 2013 was a month of extremes for the High Plains Region with a wide variety of weather ranging from record-breaking rainfall, record-breaking snowfall, record-breaking heat, and severe storms with flash-flooding, extremely large hail, high winds, and tornadoes. Much of the temperature story is washed out by the monthly averages which do not capture the wide swings in temperature. Monthly averages indicated that the eastern portion of the Region, along with central Colorado, had temperatures just below normal, while the western portion of the Region had average monthly temperatures which were just above normal. Central Wyoming was the only widespread exception with temperature departures of 2.0-4.0 degrees F (1.1-2.2 degrees C) above normal. A look at the daily temperatures showed that there were many ups and downs throughout the month and there were some interesting records set because of that. For instance, areas of eastern Nebraska had nearly a 70 degree F (38.9 degrees C) temperature swing from the 12-14 and both record lows and record highs were set during this short timeframe. Lincoln, Nebraska had a record low temperature of 31 degrees F (-0.6 degrees C) on May 12th, followed by a record high of 100 degrees F (37.8 degrees C) on May 14. The heat of May 14th was not isolated to eastern Nebraska as daily records occurred in several states including Colorado, Kansas, Nebraska, and Wyoming. In addition to the daily records, some locations had their earliest 100 degree F (37.8 degrees C) day on record. With a high temperature of 101 degrees F (38.3 degrees C), Omaha, Nebraska set a new daily high and had its earliest 100 degree F (37.8 degrees C) day on record on May 14th. This absolutely smashed the old record of May 29, 1934 (period of record 1871-2013). On average, Omaha reaches that threshold on July 10th.
- There was quite a contrast in temperatures between this spring and last. Many locations across the High Plains Region had their warmest spring on record last year, while this year, many of those same locations ranked among the coldest. Spring 2012 was characterized by an early green-up and quick planting due to hot and dry conditions, while spring 2013 had late snows and delayed planting due to cool and wet conditions. One of the most interesting contrasts between this spring and last may have occurred in Aberdeen, South Dakota which actually had back to back warmest and coldest springs. 2012's record warm spring had an average temperature of 50.4 degrees F (10.2 degrees C), while 2013's record cool spring had an average temperature of just 37.0 degrees F (2.8 degrees C). When compared to normal, the spring of 2012 was 6.8 degrees F (3.8 degrees C) above normal, while the spring of 2013 was 6.6 degrees F (3.7 degrees C) below normal.
- May was an interesting precipitation month for the High Plains Region. At the beginning of the month, snow fell across a large area of the Region and even as far south as Dodge City, Kansas. Some areas of eastern Nebraska and Kansas broke snowfall records for both daily and monthly amounts, as well as latest snowfall, and then went on to set records for the earliest 100 degree F (37.8 degrees C) day on record. For instance, Omaha, Nebraska received 3.1 inches (8 cm) of snow on May 1-2, which set a record for snowiest May. The old record of 2.0 inches (5 cm) was set in 1945 (period of record 1884-2013). About two weeks later, temperatures across the region soared and Omaha hit 101 degrees F (38.3 degrees C). Multiple storms systems ultimately crossed the Region bringing snow, heavy rain, hail, high winds, and tornadoes. In regards to precipitation, by the end of the month, it was generally a story of the 'haves' and the 'have nots' - with most locations receiving either well above or well below normal precipitation and not too many in between. Kansas had an interesting example of the differences in precipitation. For instance, Topeka had its 20th wettest May with 6.76 inches (172 mm), while Dodge City had its 17th driest May with only 0.91 inches (23 mm) (period of record for Topeka: 1887-2013, period of record for Dodge City: 1874-2013). Ample, or in some cases excessive, precipitation fell across North Dakota, the majority of South Dakota, most of Nebraska, central Colorado, northern Wyoming, and a few pockets of Kansas. Portions of these areas received extremely heavy rainfall, especially towards the end of the month, which helped improve the drought situation and in some cases brought flash flooding. Some of the heaviest precipitation occurred in North Dakota where nearly the entire western half of the state received over 200 percent of normal precipitation. Bismarck, North Dakota had a May total of 7.37 inches (187 mm). This came in at 4.97 inches (126 mm) above normal, or 307 percent of normal precipitation, easily beating the 1927 total of 7.04 inches (179 mm) (period of record 1874-2013). Another impressive total came from Bowman, North Dakota which received 10.61 inches (269 mm) and absolutely crushed the old record of 6.73 inches (171 mm) set in 1982 (period of record 1915-2013). This amount was 430 percent of normal precipitation! Other areas of the Region also received heavy precipitation including Lincoln, Nebraska which totaled 8.44 inches (214 mm). While not enough to break the record, this amount did rank as the 7th wettest May (period of record 1887-2013). The rains were quite welcome there, as this area had been dealing with drought since last year. Those missing out on the heavy precipitation this month included the western half of Kansas, eastern and southern Colorado, southern and eastern Wyoming, and just a few pockets of South Dakota and Nebraska where precipitation totals were less than 70 percent of normal. Much of southeastern Colorado and southwestern Kansas received less than 25 percent of normal precipitation. This lack of precipitation hit eastern Colorado and western Kansas especially hard since portions of that area have been dealing with drought issues since 2011. Overall, the cool, wet conditions this spring resulted in a slow start to corn and soybean planting, however, once the conditions improved producers were able to make significant progress to catch up. Unfortunately, winter wheat was still suffering as nearly half the crop remained in poor to very poor condition in Colorado, Kansas, Nebraska, and South Dakota.
- It was a late start to the severe weather season this year as colder air had been dominating the Plains and the southeast US. Interestingly, many locations were in what was being called a 'tornado drought.' But, once the severe weather season got started, May turned into an active month. Severe weather was reported somewhere in the High Plains Region on 20 days and resulted in a total of 844 reports (tornadoes, high winds, and large hail). The last week of the month was especially active with numerous confirmed tornadoes, extremely large hail, high winds, heavy rainfall, and flash flooding. While there were too many severe weather events to list each one, there were some notable ones. One tornado to note occurred north of Salina, Kansas in Ottawa County and was preliminarily rated as an EF-4. According to the National Weather Service Office in Topeka, Kansas the tornado was slow-moving and on the ground for about an hour. Luckily, no serious injuries or fatalities occurred, although some cattle were lost in the storm. A notable hail report came from near Montrose, Kansas. According to the National Weather Service in Hastings, Nebraska, a 5.25 inch hailstone was measured there.
- There were significant changes to the U.S. Drought Monitor over the past month. At the end of May, approximately 73 percent of the Region was in moderate (D1) to exceptional (D4) drought - down from 85 percent at the end of April. Ample, and in some cases excessive, precipitation helped reduce or eliminate drought in portions of each state. North Dakota is now virtually drought free, with only 0.01 percent of the state in the D1 designation. Significant improvements were also made to the extreme drought conditions (D3) in both South Dakota and Nebraska. Drought free areas have begun to emerge or grow in eastern South Dakota, southeastern Nebraska, and eastern Kansas. While much of the Region had heavy rains, portions of eastern Colorado and western Kansas missed out and D4 conditions persisted there. Like last month, Kansas had the largest area of D4 coverage with 22 percent, up just a bit from the 20 percent at the end of April. According to the U.S. Seasonal Drought Outlook released May 16th, drought conditions were expected to improve in North Dakota, South Dakota, Nebraska, eastern Kansas, northeastern Colorado, and eastern Wyoming. Drought was expected to persist elsewhere through July 2013.
- For more information, please go to the High Plains Regional Climate Center Home Page.
- Southern Region: (Information provided by the Southern Regional Climate Center)
- Unlike April, the month of May was generally a cooler than normal month for most of the Southern Region. With the exception of the north western corner of the region, temperature averages for the month ranges from 0 to 4 degrees F (0 to 2.22 Degrees C) below normal. In the Texas and Oklahoma panhandles, temperature averages were only slightly higher than normal. The state average temperature values for the month of May are: 67.40 degrees F (19.67 degrees C) for Arkansas, 71.40 degrees F (21.89 degrees C) for Louisiana, 69.20 degrees F (20.67 degrees C) for Mississippi, 66.90 degrees F (19.39 degrees C) for Oklahoma, 65.20 degrees F (18.44 degrees C) for Tennessee, and 72.50 degrees F (22.50 degrees C) for Texas. All state rankings fell within the two middle quartiles, with the exception of Louisiana which experienced its thirteenth coldest May on record (1895-2013), and Mississippi, which experienced its twentieth coldest May on record (1895-2013).
- May precipitation in the Southern Region varied significantly, with a patchy spatial pattern including areas of extreme dryness and areas of intense saturation. Within the Southern region, anomalously high precipitation totals were observed in: south east Louisiana, north eastern Arkansas, north western Mississippi, south western Tennessee, and small pockets in central Texas. Conversely, areas of dryness included: north western Texas, western Oklahoma, northern Louisiana, and along much of the northern Gulf coast of Texas. With the exception of Texas, all states reported a wetter than normal May. The state precipitation totals are as follows: Arkansas with 6.14 inches (155.96 mm), Louisiana with 5.54 inches (140.72 mm), Mississippi with 6.96 inches (176.78 mm), Oklahoma with 5.12 inches (130.05 mm), Tennessee with 5.81 inches (147.57 mm), and Texas with 2.61 inches (66.29 mm). For Mississippi, it was the nineteenth wettest May on record (1895-2013), while Tennessee experienced its twenty-fifth wettest May on record (1895-2013). All other state rankings fell within the middle two quartiles. It is noteworthy that these rankings are not indicative of the high spatial variance in precipitation since values are averaged over the entire state.
- Prolonged dryness in the north western area of Texas and in western Oklahoma over the past month has led to a significant increase in the amount of extreme and exception drought conditions. Elsewhere, drought conditions have improved as a result of some much needed rainfall. Areas of improvement include central and southern Texas, southeastern Arkansas, and central Oklahoma.
- In Texas, damages from weather this month have been higher than the most recent few months. The Granbury tornado caused an estimated $34 million in damages. Instances of vehicular damage from hail and reduced visibility following the various storm systems were common. Even after the frontal passages, dry regions were subjected to low humidity and high winds, causing fires near Possum Kingdom Lake and presenting fire danger to several other regions around the state. Several frontal passages have helped improve short-term conditions in the eastern and southern portions of the state, but not without their own problems. A storm system early in the month helped contribute to the low monthly average temperature, causing record lows in Houston and other parts of eastern Texas. Later storms brought heavy rain and flooding, cutting power to 19,000 people in Houston and killing two people in San Antonio, and an EF-4 tornado hit Granbury which destroyed over 100 homes and killed 6 people. The systems further caused dust storms in the west and school closings all across the state. (Information provided by the Texas State Climate Office).
- The most significant occurrence of severe weather in May, 2013 is without question, the tornado that struck the town of Moore, Oklahoma on May 20, 2013. The twister is estimated to have been an EF5, which is the highest ranking on the Enhanced Fujita Tornado Scale. The tornado had peak winds in and around 210 miles per hour (340 km/h). Damages from the storm are not fully calculated, however, preliminary estimates suggest that the storm caused somewhere between one and a half to two billion dollars in damage, which in not surprising considering that approximately twelve to thirteen thousand homes were destroyed or in some way damaged. According to CNN.com, a total of three hundred and seventy-seven people were reported injured and twenty-four people lost their lives. Of the twenty-four fatalities, ten were children.
- For more information, please go to the Southern Regional Climate Center Home Page.
- Western Region: (Information provided by the Western Regional Climate Center)
- Most locations in the West varied in temperature from well above to well below normal throughout May, averaging near normal for the month. A closed low pressure system mid-month brought helpful but insufficient precipitation to Southern California, the Sierra Nevada, and the western Great Basin. During the last third of May, a persistent low pressure system set up over the Pacific Northwest bringing cool temperatures and ample precipitation to the area. Late May also brought very wet conditions to eastern Montana.
- May began with increasing temperatures for much of the West. Coastal areas of California saw a smattering of daily record high temperatures throughout the month. San Francisco recorded a trio of record daily highs of 89 F (31.7 C), 85 F (29.4 C) and 84 F (28.9 C) on May 2nd-4th. Five daily high temperature records were set at Camarillo, California during the first half of the month. Temperatures at Camarillo averaged out to 67.2 F (19.6 C), 5.8 F (3.2 C) above the May norm. Further east, Tucson recorded its 2nd warmest spring with an average 71.5 F (21.9 C), but only its 10th warmest May at 78.8 F (26 C) in an 83-year record. Tucson typically logs four days over 100 F (37.8 C) in May, but recorded none this month. This was their first May since 2004 to have no days over the century mark. In the western Great Basin, Tonopah recorded its 4th warmest spring with an average 53.2 F (11.8 C) but only 19th warmest May. Further north, Spokane, Washington saw seven consecutive days with temperatures higher than 80 F (26.7 C) on the 6th through the 12th. This is the longest such stretch this early in the warm season at Spokane, where records began in 1889. May started off a bit cooler in the Rockies. The 19 F (-7.2 C) reading at Denver, Colorado Airport on the 2nd is the second lowest May reading since the station was installed in 1995.
- A closed low developed over the Southwest during the first week of the month, bringing scattered precipitation across the region. Over 4 days, May 5th-8th, Reno, Nevada, received 0.65 in (17 mm) of rain, more than the combined total of the previous four months. Bishop, California received 0.47 in (12 mm) precipitation on the 6th and 7th, the first measurable precipitation since December 26th and tied May 6 1972 for latest observance of first measurable precipitation in a calendar year. Many Southwest locations such as Phoenix and Las Vegas recorded no precipitation, not atypical for May. The Pacific Northwest began the month with warm temperatures and clear skies. Wet, cool weather then dominated the latter half of the month as a low pressure system posted over the region. Vancouver, in southwestern Washington, recorded its wettest May in a 123-year record at 4.89 in (124 m), 198% of normal. Even so, for the year, 2013 is the 4th driest on record there with 13.23 in (336 mm), 71% of normal. Further east, Yakima, Washington logged its 3rd wettest May at 2.48 in (63 mm), 428% of normal for the month. In eastern Montana, Miles City recorded 6.69 in (170 mm) precipitation, 307% of normal and the 3rd wettest May on a 76-year record. Parts of eastern Montana recorded over 10 inches of rain.
- April's below normal temperatures continued through the final week of May for Alaska's interior. Fairbanks began the month with temperatures more than 10 F (5.6 C) below normal and ended with temperatures over 10 F (5.6 C) above normal. Fairbanks recorded an average 44.3 F (6.8 C) for the month, the 5th coolest May in a 63 year record. Portions of southern Alaska saw abundant precipitation and snowfall this month. Valdez recorded 10.61 in (270 mm) precipitation, 378% of normal and the wettest May in a record that began in 1917. Valdez also logged its snowiest May on record, receiving 27.3 in (69.3 cm) total for the month.
- May (all month): Fires in the West: Several large fires occurred throughout the month in Alaska, California, New Mexico, and Arizona. One of the most destructive was the Springs Fire in Ventura County, California. Ignited on May 2, the blaze spread quickly due to strong Santa Ana winds and dry fuels. Over 24,000 acres (9,700 hectares) were consumed, 10 outbuildings destroyed and 12 structures damaged. No homes were destroyed.
- May (throughout month): Drought conditions in the West: Precipitation helped to alleviate drought conditions in a few locations along the northern tier of the West. Drought conditions worsened in New Mexico, Arizona, and northern California, where below normal precipitation was observed this month. According to the US Drought Monitor, the area of the West with no drought designation decreased from 20% to 14% in May. Areas in extreme drought status rose from 4% to 6%. This increase occurred in southeastern Colorado and New Mexico.
- May 23: Dry air over Boise, Idaho: Radiosonde observations from Boise recorded only 0.05 in (1.3 mm) precipitable water, the driest atmosphere recorded on any day in Boise since radiosonde observations began.
- May 27: Flooding in Alaska: Colder than normal temperatures this spring has slowed melting of ice along the rivers of Alaska's interior. This has resulted in ice damming and flooding at some locations. On May 27, an ice jam on the Yukon River caused flooding in the town of Galena, prompting evacuation of many of the town's 470 residents.
- For more information, please go to the Western Regional Climate Center Home Page.
See NCDC's Monthly Records web-page for weather and climate records for the most recent month. For additional national, regional, and statewide data and graphics from 1895-present, for any period, please visit the Climate at a Glance page.
PLEASE NOTE: All of the temperature and precipitation ranks and values are based on preliminary data. The ranks will change when the final data are processed, but will not be replaced on these pages. Graphics based on final data are provided on the Temperature and Precipitation Maps page and the Climate at a Glance page as they become available.