Climate Monitoring / Climate of 2007 / May / Help

Climate of 2007 - May in Historical Perspective

Including Boreal Spring

National Climatic Data Center
14 June 2007

Contents of this Report:

Selected Global Significant Events for May 2007
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Major Highlights


The fifth warmest spring on record for the contiguous U.S. occurred in 2007, according to scientists at NOAA's National Climatic Data Center in Asheville, N.C. A severe-weather outbreak in the nation's midsection brought devastating tornadoes in early May, while a record-dry spring in the Southeast led to worsening drought conditions. Continued extreme dryness in May east of the Mississippi River and in the Far West expanded the drought area. The global land-surface temperature was the highest for the month of May, as well as for boreal spring. The combined global land- and ocean-surface temperature was fourth warmest for May, and tied with 1998 as the warmest January-May period.

U.S. Temperature Highlights for May
For the contiguous U.S., the average temperature for May was 63.14°F (17.30°C), which was 2.08°F (1.16°C) above the 20th century mean and the 11th warmest May on record, based on preliminary data.

In May, most of the contiguous U.S. was warmer-than-normal with only Texas and South Carolina colder-than-normal for the month.

Alaska had its 16th warmest May since official records began in 1918, 1.40°F (0.78°C) above normal. However, spring overall was the 38th coolest for the state, 1.73°F (0.96°C) below normal.

Warmer-than-average May temperatures in the northern U.S. combined with cooler-than-average temperatures in the Southeast and parts of Texas created milder overall conditions and helped decrease residential energy needs for the nation. 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 was approximately 4.4 percent lower than what would have occurred under average climate conditions for the month.

U.S. Temperature Highlights for Spring
For spring 2007 (March-May), the average temperature for the continental U.S. was 54.38°F (12.43°C), which was 2.49°F (1.38°C) above the 20th century mean and the fifth warmest spring on record, based on preliminary data. The four warmest springs in order are 1910, 2004, 2000 and 1934.

This was the third warmest spring for Wyoming and Missouri, while it was the fourth for Illinois and Nevada. This was the fifth warmest spring on record for the Central and Western North-Central regions of the country.

Spring energy demand was closer to normal nationwide based on the REDTI (approximately 1 percent lower than average). The effect of near-average to cooler-than-average spring temperatures on energy demand for heating in the heavily populated Northeast and parts of the South was offset by warmer-than-average temperatures in the central and western U.S.

U.S. Precipitation Highlights for May
For May, the average precipitation for the continental U.S. was 2.65 inches (67.31 mm), which is 0.22 inches (5.67 mm) below the 20th century mean, but near the long-term average, based on preliminary data.

May 2007 was the driest on record for Georgia, while it was third driest for Ohio and Alabama, and the Southeast Region overall. By contrast, parts of the High Plains and Southwest were wetter than normal in May. Texas, New Mexico, North Dakota, and South Dakota all much wetter-than-normal for the month.

U.S. Precipitation Highlights for Spring
The average spring precipitation for the contiguous U.S. was 6.91 inches (175.51 mm), which was 0.80 inches (20.24 mm) below the 20th century mean and the 23rd driest spring in the observed climate record dating back to 1895.

This was the driest spring on record for Tennessee, Mississippi, Alabama and Georgia. On the regional scale, the middle third of the U.S. was wetter or much wetter-than-normal, while the Southeast Region had its driest spring on record.

Approximately 34 percent of the contiguous U.S. was in moderate-to-exceptional drought in early June, according to the federal U.S. Drought Monitor.

Drought impacts have included low streamflows and mountain snowpack, parched soils and pastureland, and numerous wildfires. The dry conditions across the Southeast worsened wildfire activity during May across Florida and southern Georgia.

Severe-to-extreme drought conditions were felt across the Southeast, with drought spreading across parts of Alabama, Mississippi, Georgia, Tennessee, Florida, and North Carolina.

The past 12 month period was driest on record for California and Nevada. The abnormally dry conditions have led to severe-to-extreme drought from the southern California coast eastward to Arizona and north along the Sierra Nevada Mountains into the Great Basin.

Global Highlights
The combined global land and ocean surface temperature for May was the fourth warmest on record, 0.95°F/0.53°C above the 20th century mean. The global surface temperature for the combined January-May period tied with 1998 as the warmest January-May on record.

Separately, the global land-surface temperature was the warmest on record for May, as well as for boreal spring (March-May) and the year-to-date period. The May ocean-surface temperature was the ninth warmest in the 128-year period of record as near-average to cooler-than-average conditions were present across the equatorial Pacific.

During the past century, global surface temperatures have increased at a rate near 0.11°F (0.06°C) per decade, but the rate of increase has been three times larger since 1976, or 0.32°F (0.18°C) per decade, with some of the largest temperature increases occurring in the high latitudes of the Northern Hemisphere.

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Report Index

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to the top Global Analysis

to the top Global Hazards and Significant Events

to the top National Overview

to the top United States Drought

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Climate Monitoring / Climate of 2007 / May / Help