Climate of 2009

May in Historical Perspective

National Climatic Data Center, 10 June 2009

Contents Of This Report:
Selected Global Significant Events for May 2009


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2008 Annual Report is available here.

Major Highlights

NOAA: U.S. Temperature Warmer than Average for May

The May 2009 temperature for the contiguous United States was above the long-term average, based on records going back to 1895, according to an analysis by NOAA’s National Climatic Data Center in Asheville, N.C.

The average May temperature of 62.5 degrees F was 1.4 degrees F above the 20th Century average. Precipitation across the contiguous United States in May averaged 3.22 inches, which is 0.35 inch above the 1901-2000 average.

U.S. Temperature Highlights

California, New Mexico, and Utah respectively had their fourth, sixth, and ninth warmest May while Nevada and Arizona registered their fifth warmest May on record. Only North Dakota, Oklahoma, and Arkansas had an average monthly temperature that was below normal.

For the January – May period, only North Dakota has experienced cooler-than-normal average temperatures. By contrast, much of the South, Southwest, and West regions have been above-normal for the period.

Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand was 1.0 percent below average in May.

U.S. Precipitation Highlights

For the contiguous United States, precipitation was above normal. Florida, 9.86 inches and Arkansas, 10.91 inches experienced their all-time wettest May.

Several other states had much-above-normal precipitation amounts, including: Virginia, Tennessee, and Alabama (each fifth wettest), Mississippi and Nevada (each eighth wettest). West Virginia and North Carolina experienced their ninth and 10th, respectively, wettest May on record.

By the end of May, moderate-to-exceptional drought covered 14 percent of the contiguous United States, based on the U.S. Drought Monitor.

About 20 percent of the contiguous United States had moderately-to-extremely wet conditions at the end of May, according to the Palmer Index (a well-known index that measures both drought intensity and wet spell intensity).

Other U.S. Highlights

The Red River at Fargo, N.D., set records for consecutive days above flood (62 days), moderate flood (37 days), and major flood (31 days) stage. Grand Forks, N.D. , also set a record with 32 straight days above moderate flood stage. Along the Illinois River, Peoria broke the record for days above flood stage with 86 days at the end of May.

Last month, 9,265 new wildfires ignited and burned approximately 312,599 acres. The number of fires ranked May 2009 second during the past decade for number of fires, and third for acreage burned. For the year to date, 41,328 fires have burned approximately 1,377,310 acres throughout America, making 2009 the worst year -- so far -- in the past decade for number of fires, and third highest year to date for acreage burned.

Report Index

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to the top Global Hazards and Significant Events

to the top National and Regional Overview

to the top United States Drought