Climate of 2008
May in Historical Perspective

National Climatic Data Center
6 June 2008

Contents of this Report:

Selected Global Significant Events for May 2008

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Major Highlights

NOAA: U.S. Has 36th Coolest Spring on Record, 34th Coolest May
Global Temperature Ranked 8th Warmest on Record for May,
7th Warmest on Record for Spring

The March-May spring season was the 36th coolest on record for the contiguous United States, according to an analysis by NOAA's National Climatic Data Center in Asheville, N.C. Separately, last month ended as the 34th coolest May for the contiguous United States, based on records dating back to 1895.

The average spring temperature, 51.4°F (10.8°C), was 0.5°F (0.3°C) below the 20th century average. The average May temperature of 60.3°F (15.7°C) was 0.7°F (0.4°C) below the 20th century mean, based on preliminary data.

The combined average global land and ocean surface temperatures for May ranked 8th warmest since worldwide records began in 1880, while the boreal spring ranked 7th warmest.

U.S. Temperature Highlights

The March-May temperatures were cooler than average from the Northwest and extending throughout the central Plains and upper Mississippi Valley. In all, 19 states had a cooler-than-average spring.

Twenty-five states were cooler than average for May. Pennsylvania was much cooler than average and ranked eighth coolest.

The unusually cool temperatures helped keep the nation's overall temperature-related residential energy demand for May above average. Based on NOAA's Residential Energy Demand Temperature Index, contiguous U.S. temperature-related energy demand was approximately 3.5 percent above average in May, but near average for spring.

Florida, Texas, and Washington were warmer than average for May.

U.S. Precipitation Highlights

For the spring, Missouri had its fourth wettest, Arkansas its sixth wettest, Indiana and Iowa their eighth wettest and Illinois its 10th wettest. For May, Arizona, Maryland, and Nebraska were much wetter than average, with Nebraska ranking fourth wettest and Maryland fifth wettest on record.

California had its driest spring on record, while Nevada and Utah had their 10th and 11th driest on record. For May, two states were much drier than average -- New Hampshire had its ninth driest May on record and Florida its 10th driest.

Rainfall improved drought conditions across parts of the northern Rockies, but moderate to extreme drought continued across parts of the Great Plains, Southeast, and Southwest. About 18 percent of the U.S. was classified in moderate-to-extreme drought at the end of May compared to 23 percent a month ago, based on the U.S. Drought Monitor.

Several strong weather systems dumped heavy rains across parts of the central Plains, Ohio Valley, and mid Atlantic states. In some areas this pattern has continued for the last six months, with Missouri and Illinois having the wettest December-May on record. By the end of May, 24 percent of the contiguous U.S. was classified in moderate-to-extreme "wet spell" conditions compared to 16 percent six months ago, based on the Palmer Index.

Global Highlights

The combined global land and ocean surface temperature for boreal spring (March-May) 2008 was 0.94°F (0.52°C) above the 20th century mean of 56.7°F (13.7°C) and ranked 7th warmest based on the 1880-2008 record.

The global land surface temperature for boreal spring was 1.87°F (1.04°C) above the 20th century mean of 46.4°F (8.1°C) and tied with 2000 as 3rd warmest.

The global ocean surface temperature for boreal spring was 0.59°F (0.33°C) above the 20th century mean of 61.0°F (16.1°C) and ranked 10th warmest.

The combined global land and ocean surface temperature for May 2008 was 0.81°F (0.45°C) above the 20th century mean of 58.6°F (14.8°C) and ranked 8th warmest.

The global land surface temperature for May was 1.26°F (0.70°C) above the 20th century mean of 52.0°F (11.1°C) and ranked 7th warmest.

The global ocean surface temperature for May was 0.65°F (0.36°C) above the 20th century mean of 61.3°F (16.3°C) and ranked 10th warmest.

Continued weakening of La Niña, the cold phase of the El Niño-Southern Oscillation (ENSO), occurred during May. The ENSO conditions are expected to tend toward neutral conditions during the next two months.

Tropical Cyclone Nargis brought heavy rain, strong winds, and high storm surge waters to Burma (Myanmar) in early May, destroying thousands of homes and killing nearly 78,000 people. Nargis was the most devastating cyclone to strike Asia since 1991 and resulted in the worst natural disaster on record for Burma.

The extent of spring 2008 snow cover over Eurasia was the lowest on record for any spring in the 42-year historical satellite record. Conversely, North American snow cover extent was slightly above average. For the Northern Hemisphere, spring 2008 was the third least extensive spring snow cover.

Report Index

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