National Overview - May 2009


NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

Maps and Graphics:

May Most Recent 3 Months Most Recent 6 Months
Most Recent 12 Months Year-to-Date US Percent Area Very Wet/Dry/Warm/Cold
Annual Summary for 2008

PLEASE NOTE: All 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. As final data become available, the most up-to-date statistics and graphics will be available on the Climate Monitoring Products page and the U.S. Climate at a Glance Web site.

For graphics covering periods other than those mentioned above or for tables of national, regional, and statewide data from 1895-present, for May, last 3 months or other periods, please go to the Climate at a Glance page.


National Overview:

  • Temperature Highlights
  • For the contiguous United States, the average temperature for May was 62.5°F (16.9°C), which was 1.4°F (0.8°C) above the 20th century mean and ranked as the 24th warmest May on record, based on preliminary data.
  • On the regional level, much of the Southwest, West, and Northwest deviated significantly from the norm.
  • Based on 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 1.0% below average consumption. The Spring 2009 REDTI was the 32nd lowest value in 115 years which is 4.0% below the mean.
  • Precipitation Highlights
  • This was the 22nd wettest May in the 1895-2009 record. An average of 3.22 inches (82 mm) fell across the contiguous U.S. this month, which is 0.35 inch (9 mm) above average.
  • The Southeast region experienced its second wettest May in 115-years of record-keeping. In contrast, the West North Central region had their sixth driest May and the East North Central region was also below normal. Above-normal precipitation fell in all remaining regions except the South and West where near-normal precipitation occurred.
  • For the contiguous United States as a whole, precipitation was above normal. Both Florida (9.86 inches) and Arkansas (10.91 inches) experienced their all-time wettest May. The last time Florida saw a record wet May was in 1976 when 9.15 inches of precipitation fell. Arkansas experienced its last record wet May in 1930 when 10.07 inches of precipitation fell.
  • Other Items of Note
  • Spring (March-May) 2009 ended with the contiguous U.S. averaging 52.7°F which is 0.9°F above normal. The contiguous U.S. was also 0.64 inch above normal in terms of precipitation, which was the 24th wettest spring on record. Based on 115 previous spring years, 2009 was Georgia's second wettest.
  • ENSO-neutral conditions were present in the tropical Pacific Ocean by the end of May. Sea-surface temperature averages increased for the fifth consecutive month across much of the equatorial Pacific Ocean. According to the Climate Prediction Center, current observations, recent trends, and dynamical model forecasts indicate that conditions are favorable for a transition from ENSO-neutral to El Niño conditions during June-August 2009. For additional information on ENSO conditions, please visit the NCDC ENSO Monitoring page and the latest NOAA ENSO Advisory.
  • The Red River at Fargo, ND set records for consecutive days above flood (62 days), moderate flood (37 days), and major flood (31 days) stages. Grand Forks, ND also set a record with 32 consecutive days above moderate flood stage. Along the Illinois River, Peoria broke the record for days above flood stage with 86 days and counting at the end of May.
  • A wet April followed by a wet May across the central Midwest led to significant planting delays across much of the Midwest. At the beginning of May only Minnesota and Iowa were ahead of schedule, with the remaining states significantly behind. As of May 3rd, only five percent of the corn was planted both in Illinois and Indiana, compared to a five-year average of 66 percent and 47 percent, respectively.

For additional details about recent temperatures and precipitation across the U.S., see the Regional 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.


Regional Highlights:

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)
  • Temperatures in May averaged very close to normal, only 0.1 degree F (0.1°C) above the 30-year mean, making this the 4th consecutive warmer-than-normal month. The monthly average of 56.5°F (13.6° C) was 3.2 degrees F (1.0°C) warmer than May 2008 and 1.2 degrees F (0.7°C) cooler than May 2007. Three states, New Hampshire, New York and Rhode Island, had temperature averages that were exactly normal. The states with the greatest positive departures were West Virginia (1.0°F, 0.6°C above normal) and Delaware (1.5°F, 0.8°C above normal). Vermont was the coolest state, with an average temperature that was 1.1°F (0.6°C) below normal. In general, the coolest readings occurred on the 19th or 20th, while the highest temperatures were recorded from the 21st to the 25th.
  • The dry trend in the Northeast was put on hold this month as precipitation totals were above normal in much of the region. The Northeast, on average, received 4.67 inches (118 mm) of rain, which was 117% of normal. While Vermont was the driest state in April, it was the wettest in May, with 144% of the normal May rainfall amount. West Virginia was close behind, at 141% of normal rainfall. It was the 9th wettest May in West Virginia. Connecticut (87%) and Rhode Island (79%) were the driest states this month.
  • The Northeast was in good shape, drought-wise, at the end of May. Only a small portion of northeastern Pennsylvania, northern New Jersey and a bit of New York along the PA-NJ border had abnormally dry conditions according to the US Drought Monitor dated June 2, 2009.
  • On May 16 an EF0 tornado touched down in Cuyler, Cortland County, NY, destroying 2 sheds and uprooting some trees. As the line of thunderstorms moved east, a more intense tornado (EF2, winds as high as 120 mph, 48-54 m/s) touched down in Georgetown, Madison County, NY. Two large barns, a silo and a few outbuildings were destroyed, some livestock were lost and one injury was reported.

    In a state not known for tornado activity, Maine had 2 weak tornados touch down this month. The first was a strong F1 tornado on the 24th in Eagle Lake, Aroostook County. Damage from winds up to 110 mph (49 m/s) included uprooted and sheared trees, home and vehicle damage and one destroyed outbuilding. The second tornado occurred on May 31 in east central Aroostook County, ME. At first touchdown, max wind speed of about 65 mph (29 m/s) sheared off or uprooted dozens of trees. A half hour later, with winds up to 75 mph (33 m/s), the tornado sheared off hundreds of trees and damaged or destroyed a few buildings.

  • Temperatures averaged 1.0 degree F (0.6°C) above normal during Spring 2009. Maryland, at 0.1° F (0.1°C) below normal, was the only state with a negative departure during this time period. New Hampshire and West Virginia were the warmest states, with positive departure of 1.3°F (0.7°C) and 1.4°F (0.8°C), respectively. The region's three-month precipitation average was 10.3 inches (26.2 cm), or 93% of normal. West Virginia (105%), Maryland (102%) and Delaware (100%) were the only states at or above normal. With 75% of the normal spring precipitation amount, Connecticut was the driest state.
  • For more information, please go to the Northeast Regional Climate Center Home Page.
  • Midwest Region: (Information provided by the Midwest Regional Climate Center)
  • Temperatures were cool, as much as 5°F to 8°F (3°C to 5°C) below normal, in northwest Minnesota. Temperatures across the rest of the region were within 2°F (1°C) of normal. A significant cold snap on May 17 and 18 brought record cold temperatures to the southern two-thirds of the region. Strong southerly winds combined with dry conditions led to a rapid warming in Minnesota, Wisconsin, and Michigan just days later. Record warmth spread across the three states on May 19-21 with monthly records at Gaylord, Minnesota (May 20 97°F (36°C)) and Big Bay, Michigan (May 21 94°F (34°C)).
  • Precipitation varied from below 50% of normal in northwest Iowa, central Minnesota, and northwest Wisconsin to nearly 200% of normal in eastern Kentucky and south of the confluence of the Mississippi and Ohio Rivers. Northwest Minnesota was also well above normal for the month. Dry conditions persisted across southern Minnesota, northwest Wisconsin, and upper Michigan in May extending the drought in those areas.
  • A wet April followed by a wet May across the central Midwest led to significant planting delays across much of the Midwest. At the beginning of May only Minnesota and Iowa were ahead of schedule, with the remaining states significantly behind. As of May 3 only five percent of the corn was planted both in Illinois and Indiana, compared to a five-year average of 66 percent and 47 percent, respectively. Conditions improved and planting increased about the middle of the month, with the biggest surge during the week ending May 24. This was a sunny, dry, and warm week, and corn planting jumped to 62 percent complete in Illinois and 55 percent complete in Indiana. By the end of the month planting was complete in Iowa, and 90 percent to complete in Minnesota, Wisconsin, Ohio, and Missouri. Corn planting was 89 percent complete in Kentucky, 82 percent complete in Illinois, and 78 percent complete in Indiana. Some of the remaining corn acreage may be planted in soybeans due to the lateness of the season. Soybean planting, which typically starts later than corn, was also well behind schedule except in Iowa, Minnesota, Wisconsin, and Ohio.
  • There were fatalities in the Midwest due to tornadoes, severe thunderstorms, and flooding during the month. On May 8, tornadoes killed in two in Kentucky and one in Missouri. Two additional fatalities were associated with severe thunderstorms in Missouri on May 8. May 13 brought two deadly tornadoes to Missouri causing three deaths. Flooding the night of May 16 along the Spoon River in Illinois washed two cars into the river, killing the driver in each case.
  • The Red River at Fargo, ND set records for consecutive days above flood (62), moderate flood (37), and major flood (31) stage. Grand Forks, ND also set a record with 32 consecutive days above moderate flood stage. Along the Illinois River, Peoria broke the record for days above flood stage with 86 days and counting at the end of May.
  • For details on the weather and climate events of the Midwest during May, see the weekly summaries in the MRCC Midwest Climate Watch page.
  • Southeast Region: (Information provided by the Southeast Regional Climate Center)
  • Mean temperatures for May 2009 were slightly above normal across much of the region. Temperatures were slightly below normal over small portions southern GA, extreme southern FL, west central NC, and NW VA. In Puerto Rico, temperatures were slightly below normal across much of the island. There were relatively few record low temperatures set during the month and most of these were observed behind a cold front that passed through on the 17th of the month. Low temperatures of 39°F (4°C) and 35°F (2°C) were observed at Spartanburg, SC and Asheville, NC, respectively, on the morning of the 19th. Normally, the coldest temperatures during the month of May occur during the first week or so of the month; however, they were not observed until the 19th and 20th of the month. Mt Mitchell, NC, Bland and Burkes Garden, VA recorded daily minimum temperatures of 28°F (4°C). There were numerous warm days during the month, but very few of these days were exceptionally hot at any location. The greatest daily maximum temperature for the month for each state, with one exception, occurred on a unique date. The dry conditions at Devils Garden in the Everglades region of FL contributed to a record daily high temperature of 101°F (38°C) on the 11th. Wakefield, VA and Jacksonville, NC recorded the highest daily maximum temperatures in their respective states on the 9th and 10th of the month, however the recorded high of 91 degrees at both stations was not exceptional when compared with records for stations in the region with long running records.
  • Much of the region displayed above normal precipitation totals for May. Monthly precipitation totals were more than 200 % of normal across much of FL, portions of AL, eastern GA, southeastern SC as well as small portions of NW NC and western and northern VA. Northeastern and central FL were exceptionally wet with many locations reporting precipitation totals exceeding 300% of normal. There were many precipitation records broken. Most notably, Daytona Beach, FL recorded 22.33 inches (567 mm), which was 19.07 inches (484 mm) above average for the month of May. This ranked as the wettest May on record and the 2nd wettest month for a record extending back to 1923. Much of the precipitation fell between the 18th and the 20th of the month as an upper level cyclone and attendant surface low pressure drifted slowly northwestward across central FL into the northern Gulf of Mexico. Daytona Beach recorded 15.73 inches, which ranked as the second wettest 3-day period in the record. Exceptionally wet conditions were also observed across portions of the southern Appalachians. Asheville, NC and Christiansburg, VA recorded 9.18 inches (233 mm) and 12.28 inches (312 mm) of precipitation for the month, respectively. Both of these totals broke records for the month of May. Also, Washington Dulles recorded 10.26 inches (261 mm) of precipitation, which was also more than 6 inches (152 mm) above normal. Below normal precipitation totals for the month were confined to small portions of eastern and central NC, central GA, and the western panhandle of FL. Panama City, FL recorded only 1.67 inches (42 mm) of precipitation for the month, which was less than 50% of normal.
  • The heavy precipitation observed across much of the region provided continued relief from the lingering drought across small portions of the Southeast. The area of extreme drought (D3) in southwestern FL was reduced to moderate drought (D2). The small region of moderate drought (D2) in western NC and extreme NE GA disappeared, although abnormally dry conditions persisted across portions of the region. A few groundwater monitors southwestern NC indicate that water table levels there have not fully recovered. There were 59 reports of tornadoes across the region during the month of May. More than half of these tornadoes occurred across AL during the first week of the month along with 19 tornadoes in NC. An early season tropical depression formed well off of the Virginia coast on the 28th and moved northeasterly well away from land. A fast moving line of strong thunderstorms (i.e. derecho), produced strong straight-line winds across northern and central GA on the 2nd and 3rd resulting in the downing of numerous trees. The exceptionally wet conditions in southern GA lead to an outbreak of mosquitoes. This prompted health authorities in Lowndes Co. GA to issue a health emergency as mosquitoes have the potential to carry diseases, such as West Nile virus. The heavy rainfall in NC contributed to several landslides along US Highway 64 in Henderson Co. as well as erosion of some small sections of US Highway 421 along a creek near North Wilkesboro.
  • 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)
  • This May the High Plains Region was near normal with common average monthly temperature departures ranging from 2°F (1.1°C) above normal to 2°F (1.1°C) below normal. The exceptions were North Dakota and Colorado where average monthly temperature departures were as large as 6°F (3.3°C) below normal and 8°F (4.4°C) above normal, respectively. The cool temperatures in North Dakota were not record breaking however, Cheesman, CO recorded its 4th warmest May with an average temperature of 55.0°F (12.8°C), which was 6.8°F (3.8°C) above normal.
  • May 2009 was a month of record setting dryness across the High Plains Region as a weak precipitation pattern dominated. Most of the Region received less than 70% of normal precipitation and large swaths received less than 50% of normal precipitation. Ultimately, several locations across the region recorded the driest May on record. This month's extreme dry location was Wamego 4W, KS which broke a 108 year record by receiving only 0.52 inches (13.2 mm) of precipitation. The old record of 0.92 inches (23.4 mm) was set back in 1901.

    While the vast majority of the High Plains Region was dry, western Colorado, and small portions of Kansas, Nebraska, and North Dakota received above normal precipitation. This month's extreme wet location was Leadville, CO. The Leadville Lake County Airport recorded its wettest May with 2.66 inches (67.6 mm), or 422% of normal precipitation. Of this monthly total, 0.82 inches (20.8 mm) fell in one day (May 31), which set a daily record. Interestingly, this daily record was over 1000% of the previous record of 0.07 inches (1.8 mm) set back in 1983.

  • May was another dry month for portions of the High Plains Region with many locations currently 3-6 inches (76.2-152.4 mm) below normal for the year. The combination of cool temperatures and ample soil moisture staved off drought conditions, but stress on some emerging crops is now evident. Since last month, the abnormally dry conditions (D0) in eastern Nebraska and north-central Kansas have expanded to include much of South Dakota and a portion of the Nebraska panhandle. In the western portion of the High Plains Region, drought conditions have improved. In south-central Colorado moderate drought conditions (D1) have been downgraded to D0 and portions of the D0 in both Wyoming and Colorado have been erased. According to the U.S. Seasonal Drought Outlook released on May 21, drought conditions in Colorado and Wyoming are expected to improve through August 2009.
  • For more information, please go to the High Plains Regional Climate Center Home Page.
  • Western Region: (Information provided by the Western Regional Climate Center)
  • Except for portions of the Pacific Coast and a strip extending south from the Canada-US border, the West experienced above to well above normal temperatures, especially in the Southwest. Las Vegas, NV, had their warmest May on record dating back to 1937. Winslow, AZ, recorded their second warmest May on record going back 101 years, while Tucson also recorded their second warmest May on record dating back 60 years. Many cities in California recorded a near record May as well.
  • Precipitation was a mix of above and below normal. Most of Arizona, southwest New Mexico, a large area centered around the Four Corners, Northern California and the coastal Pacific Northwest were wetter than usual. Conditions were especially dry in much of Nevada and in southern California, as well as all of Montana and most of Wyoming. Parts of the Southwest experienced the wettest May on record while other Southwest locations received little or no rain. Holbrook, AZ, measured an incredible 3.50 inches (89 mm) on the 22nd. This was not only the greatest one-day rainfall event for Holbrook dating back to 1893, but was more than twice the greatest May total ever. May is Holbrook's driest month with an average of only 0.29 inches (7.4 mm). Page, AZ, received 2.34 inches (59 mm) of rain from the 21st to 23rd and 2.36 inches (60 mm) for the month. This was their wettest May on record. On average, May is the second driest month in the Southwest, just behind June. Although 0.67 inches (17 mm) of rain may not seem like much, it was the third greatest May total in Tucson dating back 60 years. Most of New Mexico and Utah, however, were below normal. The Pacific Northwest had an above normal month while Montana, Wyoming and Southern California had a very dry May. It was the third driest May on record in Billings going back to 1948.
  • For more information, please go to the Western Regional Climate Center Home Page.

See NCDC's Monthly Extremes web-page for weather and climate records for the month of May. For additional national, regional, and statewide data and graphics from 1895-present, for May, the last 3 months or other periods, 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 Climate Monitoring Products page and the Climate at a Glance page as they become available.

Citing This Report

NOAA National Climatic Data Center, State of the Climate: National Overview for May 2009, published online June 2009, retrieved on July 24, 2014 from http://www.ncdc.noaa.gov/sotc/national/2009/5.