U.S. National Overview

May 2008

• For the contiguous United States, the average temperature for May was 60.3°F (15.7°C), which was 0.7°F (0.4°C) below the 20th century mean and ranked as the 35th coldest May on record, based on preliminary data.

• On the regional level, much of the U.S. experienced cooler than normal temperatures during May. Five regions had below average temperatures and the remainder experienced near average temperatures. A persistent southerly track of the jet stream drove several cold fronts and low pressure systems across the central to northeastern parts of the U.S. during May, resulting in cool and stormy weather.

• During May, three states (Florida, Texas, and Washington) were warmer than average, while twenty-five states were cooler than average for the month, based on statewide data going back to 1895. Pennsylvania was much cooler than average and ranked as the eighth coolest May in the 1895-2008 record.

• Using the Residential Energy Demand Temperature Index (REDTI - an index developed at NOAA to relate energy usage to climate), the nation's residential energy demand during May was approximately 3.5% above average consumption and ranked as the 18th highest May value in 114 years.

• This was the 40th wettest May in the 1895—2008 record. An average of 3.0 inches (77 mm) fell across the contiguous U.S. this month, which is 0.16 inches (4 mm) above average.

• On the regional level, much of the U.S. received near normal levels of precipitation in May. The West North Central U.S. was the 15th wettest, and the Central region was also above normal. Only the Southeast experienced below-average precipitation during the month.

• Three states (Arizona, Maryland, and Nebraska) were much wetter than average for May, with Nebraska ranking fourth wettest and Maryland ranking fifth wettest in the 1895-2008 record. Two states were much drier than average, with New Hampshire having the ninth driest May on record and Florida ranking tenth driest.

• The spring (March-May) temperature for the contiguous United States (based on preliminary data) was 51.4°F (10.8°C), 0.5°F (0.3°C) below the 20th century average, making the season the 37th coolest since records began in 1895.

• Statewide spring temperatures were cooler than average from the Northwest eastward through the central plains and upper Mississippi Valley. Only five states (Texas, Delaware, New Jersey, Connecticut, and Rhode Island) were warmer than average for the spring, while nineteen states were cooler than average for the season.

• The spring REDTI was the 54th lowest value in 114 years. Our current model indicates the national residential energy consumption was 0.2% below the mean period of record consumption.

• During spring, an average of 8.0 inches (203 mm) fell across the contiguous U.S., which is 0.3 inches (7 mm) above average, making the season the fortieth wettest on record.

• California had the driest spring on record, while Nevada and Utah had their tenth and eleventh driest springs on record, based on preliminary data. Conversely, parts of the central Mississippi valley received much above normal precipitation during the spring. Missouri had the fourth wettest spring, Arkansas the sixth, Indiana and Iowa the eighth wettest, and Illinois the tenth wettest spring in the 1895-2008 record.

• The West had the driest spring on record, with an average of 1.3 inches (34 mm) of precipitation, which is 3.1 inches (78 mm) below average. The Central region had the fifth wettest spring on record, and the third wettest January-May on record.

• Based on preliminary reports, 595 tornadoes were reported in the contiguous U.S. during May, resulting in 43 fatalities. A total of 112 fatalities have been reported for the first five months of 2008, which is the most for January-May since 1998. For more information on tornadoes this season, please see the NCDC 2008 Tornado Season page.

• La Niña conditions were present in the tropical Pacific Ocean at the end of May. Equatorial sea-surface temperatures (SSTs) remained below average in the central Pacific Ocean, although these negative departures have weakened considerably since mid-February 2008. According to the CPC, recent equatorial Pacific SST trends and model forecasts indicate a transition to ENSO-neutral conditions during the next two months. A weakening La Niña may result in drier than normal conditions in the Pacific Northwest and wetter than normal conditions in Alaska, New England, and the eastern Gulf coast, as well as above average temperatures in the intermountain west, southwestern U.S., and the Northeast, and cooler than normal temperatures in the central Mississippi Valley through the far southeastern U.S. in the next three months. For additional information on ENSO conditions, please visit the NCDC ENSO Monitoring page and the latest NOAA ENSO Advisory.

• Alaska had its 24th warmest May since records began in 1918, with a temperature 0.5°F (0.3°C) above the 1971—2000 average.
  
  
• Alaska had its 29th warmest March—May on record, with a temperature 1.0°F (0.6°C) above the 1971—2000 average.
  
  
• Alaska had its 33rd warmest January—May on record, with a temperature 0.03°F (0.02°C) below the 1971—2000 average.

For additional details about recent temperatures and precipitation across the U.S., see the Monthly and Seasonal Highlights section below and visit the May Climate Summary page. For information on local temperature and precipitation records during the month of May, please visit NCDC's Extremes page. For details and graphics on weather events across the U.S. and the globe please visit NCDC's Global Hazards page.

• The Northeast's average temperature flip-flopped from the previous month. While April was much warmer than normal, May's average temperature was 2.7°F (1.5°C) below normal. New York and Pennsylvania were the coldest states, with departures of -3.3°F (-1.8°C) and -3.7°F (-2.1°C), respectively. It was the 8th coldest May since 1895 in Pennsylvania, the 14th coldest in West Virginia and the 17th coldest in Maryland and New York. Maine temperatures were the closest to normal, with a departure of only 0.9°F (-0.5°C). The first day of the month gave an indication of what was to follow as several low temperature records were broken that day in CT, NH, NY, PA, and VT. Montpelier, VT reached a new record low of 24°F (-4.4°C), 3°F (1.6°C) below the previous record set in 1969.
  
  
• The southern states saw above normal precipitation totals while New York and the New England states averaged below normal. As a whole, the Northeast received 3.50 inches (88.9 mm) or 88% of the normal rainfall for May. Among the 12 states, Maryland was the wettest, with 158% of normal rainfall and New Hampshire the driest, at 40% of their normal May precipitation amount. It was the 9th driest May since 1895 in New Hampshire and the 13th driest in Vermont. At month's end, only a small area in southern West Virginia was still experiencing abnormally dry conditions.
  
  
• According to WCHS-TV in Charleston, WV, 6 million honeybees and 100 tons of corn syrup were imported to West Virginia from Georgia. The West Virginia state legislature provided $200,000 during the 2007 session for the program, which will help state apiarists recover from prolonged drought and last years late freeze that sent commercial bee numbers down two to three times the rate of typical winters. The first shipments of corn syrup in late 2007 and early 2008 were used to help feed existing bee colonies. The replacement bees were delivered in April and May. "When replacement bees are delivered, the state should have 20 percent more bees than it did to start 2007," said Commissioner of Agriculture Gus R. Douglass. "Not only will this help ensure honey production levels, it will put our beekeepers in a stronger position to use their colonies for out-of-state crop pollination, which can be more lucrative than selling honey."
  

• May was cooler than normal across the entire Midwest, although there was a large gradient in the temperature departures from south to north. Average daily temperatures ranged from about 1°F (0.6°C) below normal in southwestern Missouri to more than 8°F (4.4°C ) below normal in northern Minnesota. Most of the region north of the Ohio River experienced temperatures 3°F (1.7°C) to 5°F (2.8°C) below normal. Growing degree days accumulated since April 1 were 85% of normal for the Midwest, ranging from 70% of normal in Minnesota to 95% of normal in Ohio.
  
  
• Precipitation was generally near to well above normal across the southern two-thirds of the region, and from 50-75% of normal across the northern third. The heaviest precipitation, from 150-200% of normal, occurred in two bands. One extended across the central third of Ohio, and a second extended from southwestern Missouri eastward across southern Illinois into southern Indiana. Notable dry areas were southeastern Kentucky, where precipitation was about 60% of normal, and in northwestern Minnesota, where precipitation was less than 50% of normal in some locations. The return of drier weather to northwestern Minnesota resulted in the depiction of Moderate Drought (D1) in that area in the May 20 U.S. Drought Monitor. The cool, wet weather slowed progress in spring planting of corn and soybeans in the Midwest during the month. During the first half of May, corn planting was 30-50% behind the five year average. Several brief periods of dry weather during the last half of the month helped producers make progress, and by the end of May, corn planting was 80-95% complete, only 5-10% behind normal.
  
  
• Severe weather ramped up during the month, and included three strong tornadoes which resulted in multiple fatalities. On May 10 a long-track tornado crossed into southwestern Missouri from Oklahoma. This tornado, on the ground for a distance of 74 miles, was a mile wide at times, causing extensive damage and at least 16 fatalities in Missouri. On May 25, a tornado rated EF5 struck Parkersburg, IA (Butler County), destroying the southern half of the town. The tornado ranged from one-half to three-quarters of a mile wide and was on the ground for more than an hour, traveling 43 miles. The storm caused seven fatalities and injured more than 70 people. A preliminary estimate by the Federal Emergency Management Agency and the Iowa Homeland Security and Emergency Management Agency attributes $5.8 million in damages to the storm, most in Butler County. The last time an EF5 tornado occurred in Iowa was on June 13, 1976. The same day, a tornado rated EF3 touched down in Anoka County, MN, destroying at least 50 homes and seriously damaging 100 others. The tornado resulted in the death of a 2-year-old child in Hugo, MN and seriously injured eight other people.
  

• May was, in general, a cool month for much of the Southeast. Most of the north, which commonly experiences its first day over 90°F (33°C) around the middle of the month, had to wait until almost the end, with some stations still waiting as June started. Thus, much of the area was close to or a little below normal. The great exception was southern Florida, where 58 daily high temperature records were set or equaled. Leading this was Royal Palm Ranger Station in Dade County, which recorded a high of 102°F (38.88°C) on May 18. This is the warmest May temperature on record and the 3rd warmest all-time high temperature. The warmest was 106°F (41°C) on October 17 and 18, 2006. Overall, this station recorded six days over 100°F (37.77°C) during May. Records began at this station in 1949.
  
  
• May started off wet in Puerto Rico, with some flash flooding reported in the municipality of Utuado on the 1st and 2nd. The island was also hit with heavy rain and flooding on May 23. However, total amounts were generally around normal. The rest of the Southeast region had a series of cold frontal passages, some bringing severe weather, which resulted in rain throughout the region. Some areas, such as northern Virginia or northwest Alabama, were a little wetter than normal while other areas, such as the DC area, received about 200% of normal precipitation in May. However, other parts of the region, such as southeast Alabama and the Tennessee, North Carolina, Virginia border region were a little drier than normal.
  
  
• The stormy nature of the month began with golf ball-sized hail in Sumter, SC on the 5th and around 2 inches (50 mm) of rain at spots along the coast of the Carolinas. This was followed by another round of severe weather that started in north Alabama on the 7th and moved through almost the entire region except the extreme south at one period or another by the 11th. An EF1 tornado in Marion County, Alabama on May 10 blew down thousands of trees and damaged mobile homes in the area. This was the first of a series of days with tornadoes in the region. The worst tornado day in May was on Mothers Day, May 11, with 15 tornadoes reported in Georgia, including an EF4 Tornado in McIntosh County, on the North-Central Coast. This was the first EF4 tornado in the state of Georgia since November 22, 1992. A few days later, several EF0 tornadoes hit Florida and Alabama on the 15th. Lastly, EF1 tornadoes hit SC, NC and AL on May 20.
  

• May 2008 temperatures remained at or below normal (0-6°F/0-3°C below) for the majority of the High Plains region. The exception to the normal or below normal temperatures occurred in eastern Colorado and southwestern Kansas, where warmer than normal temperatures (2-4°F/1-2°C) were experienced. The most extreme departures from normal temperature occurred in southwestern Kansas (4°F/2°C above) and eastern North Dakota (8°F/4°C below).
  
  
• May proved to be a diverse month precipitation-wise for the High Plains region. Two distinct areas, Colorado and North Dakota, were characterized by well below normal precipitation amounts. Some areas received as little as 5-25% of normal precipitation for the month. On the other end of the spectrum were three areas, western South Dakota, central and eastern Nebraska, and north-central and southern Kansas, that received well above normal precipitation for the month. Portions of each area received as much as 300% of normal with wide spread areas over 100% of average.
  
  
• On May 22-23, a storm system swept through central Nebraska, dumping 6.25 inches (159 mm) of rain in the McCook, NE area. Of that total, over 5 inches (127 mm) was recorded on the 23rd. The same system dropped a little over 4 inches (102 mm) in Grand Island, NE with 2.5 inches (64 mm) occurring on the 23rd. On the 26th, south-central Kansas experienced a series of thunderstorms that dropped large amounts of precipitation. Wichita, KS reported nearly 3.25 inches (89 mm) while Hutchinson, KS reported nearly 2.25 inches (57 mm). On the other extreme, Montpelier, ND recorded 0.38 inches (10 mm) during May, Hugoton, KS recorded just 0.20 inches (5 mm), and Las Animas, CO recorded 0.42 inches (11 mm) during May, all well below 25% of the average monthly precipitation for each respective station.
  

• Within the Southern region, May average temperatures were generally only a few degrees from normal, with the exception of the southern half of Texas where temperatures ranged from 3-5°F (2-3°C) above normal. One new record temperature worth noting was recorded at Dalhart Municipal Airport, where the minimum temperature reached a cool 28°F (-2°C) on May 2nd, setting a new record low. The previous record was 29°F (-1.7°C), set in 1954 and tied in 1967. On the opposite end of the spectrum, a maximum temperature of 112°F (44.4°C) was recorded at Winkler, TX on May 31, breaking the previous record of 110°F (43°C) set in 2003.
  
  
• May precipitation totals in the Southern region were generally quite variable. This is partially attributable to the annual shift from frontally dominated precipitation patterns to the formation of convective weather systems, which can be quite localized. The driest portions of the region included southern Texas, where precipitation totals were as low as 5-10% of normal for the month. For example, Victoria Regional Airport recorded only 0.3 inches (8 mm) of precipitation for the month, which equates to only 6% of normal. Pockets of anomalously high monthly precipitation totals were observed in southern Louisiana, northern Mississippi and western Tennessee, northeastern Oklahoma, and the Arkansas/Louisiana/Texas border region. Some of the wettest portions of the Southern region include: Lubbock, TX (5.16 inches/ 131.06 mm or 223% of normal), Waco, TX (10.78 inches/ 273.81 mm, or 242% of normal), and Shreveport, LA (11.56 inches/ 293.62 mm, or 220% of normal).
  
  
• With spring in full swing, numerous instances of severe weather occurred in the Southern region during the month of May. In total, over 70 tornadoes and over one hundred hail events were reported by NOAA's Storm Prediction Center in the region. The most significant weather system occurred on the evening of May 1 and the early morning of the 2nd, when 53 preliminary tornado reports were filed, predominantly in Arkansas. The northern portions of the state were hit hard as the storms claimed seven lives, destroyed or damaged over 400 homes, and cut electricity and telephone service for thousands of citizens. The storm damage spanned 18 counties in the state, 11 of which were declared disaster areas by the Governor of Arkansas. The same storm system produced lesser amounts of damage in Tennessee, Mississippi and Louisiana.
  

• May temperatures throughout the West ranged from 2-4°F (1-2°C) below normal in the intermountain region and parts of the Southwest to 2-4°F (1-2°C) above normal in parts of California and the Northwest. Temperatures fluctuated widely throughout the region for the month. Record setting heat from May 17-20 gave way to record cold a few days later in many portions of the West. Las Vegas, NV, reported a high temperature of 108°F (42°C) on the 19th, a new record for the date. Four days later, on May 23rd, the high temperature was 67°F (19°C), a new record low maximum for the date. Death Valley, CA, recorded their earliest 120°F (49°C) reading ever on May 19th, while Seattle recorded their earliest 90°F (32°C) reading ever on the 17th. Astoria, OR, reached 93°F (34°C) on the 16th, setting a new maximum temperature record for May. The first week of the month broke several low temperature records for May in numerous locations including Burns, OR, with 13°F (-11°C) on the 1st and Pueblo, CO, with 24°F (-4°C) on the 3rd.
  
  
• May precipitation was a mixed bag as well. Portions of Wyoming and Montana recorded an extremely wet month, while the Pacific Northwest and California were quite dry. Lander, WY measured 6.13 inches (156 mm) of precipitation, breaking their all-time May record. Some of the highest elevations of Wyoming and Montana actually saw an increase in the snow pack from May 1st to June 1st. Flagstaff, AZ, recorded their snowiest May ever with 8.7 inches (22 cm). In contrast, San Francisco had no measurable rain in May, contributing to their driest spring (March-May) on record with 0.47 inches (12 mm) of precipitation. Normally San Francisco receives 24% of their annual rainfall during these three months. This year, spring brought only 3% of the 2007-2008 precipitation season total to date (since July 1). Preliminary data from the WRCC California Climate Tracker shows the driest March-May statewide average in the 114-year record extending from 1895, with only 22% of the long-term mean. Although most of California was dry, an unusual event on the 23rd produced locally heavy rain and even tornadoes in the mountains of southern California that led to local flash flooding, mudslides and road closures. Over 2 inches (51 mm) fell in some locations in the morning hours of the 23rd. Bakersfield, CA measured 0.08 inches (2 mm) on the 23rd, ending an 87-day period with no measurable rain.
  
  

• The daytime highs across the Alaskan panhandle varied from near normal to several degrees below normal for the first three weeks of May and were warmer than normal towards the end of the month. Numerous new high temperature records were set on May 24-25 in this region. Central Alaska experienced somewhat above normal temperatures in the first half of the month followed by cooler than normal temperatures in the second half, bringing the monthly average at Fairbanks to 1.1°F (0.617deg;C) above normal. The Fairbanks airport recorded a low of 32°F (0°C) on May 30, which could be the second latest freeze in the last 45 years, assuming no additional freezes this season.
  
  
• Precipitation in the Alaskan panhandle was mixed, with northern and central outer coastal locations seeing only 67-77% of normal rainfall while the central inner channel and southern locations received from 111-151% of normal rainfall amounts. It was the second wettest and third snowiest May on record in Kodiak. May precipitation amounts in Fairbanks were slightly below normal and came solely in the form of rain, as expected. Barrow set a new snowfall record of 2 inches (5.1 cm) on May 27th, doubling the previous record set in 1950. Nome also broke a snowfall record when 1.8 inches (4.6 cm) fell the same day.
  
  
• The total winter snowfall in Bethel, AK was the second highest in the past 30 years. On May 23rd, King Salmon set a new two minute average wind speed record of 55 mph (89 km/hr) with peak gusts of 69 mph (111 km/hr).