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NOAA's summer 2002 temperature rankings.September 13, 2002 — The June through August 2002 summer season was much warmer and drier than average in the United States, according to scientists at NOAA’ National Climatic Data Center in Asheville, N.C. For the contiguous United States, the average temperature was the warmest since the 1930s, and drought affected approximately half of the country throughout much of the summer. The global average temperature was the third warmest on record for the June-August season. (Click NOAA image for larger view of summer 2002 temperature rankings. Click here to see more graphics.)

The average temperature for the contiguous United States was 73.9 degrees F (23.3 C) during the June through August summer season (based on preliminary data), 1.8 degrees F greater than the 1895-2001 long-term mean, making it the third-warmest summer since national records began in 1895. No state was significantly cooler than average and 17 states were much warmer than average. The warmest average summer temperature for the contiguous United States occurred in 1936 and the second warmest in 1934.

Twenty-nine states had significantly below-average precipitation, while the only states with a significantly wetter than average summer were in the upper Midwest (Wisconsin, Minnesota, Iowa and North Dakota) and parts of the southern United States (Texas and Florida). Heavy rainfall alleviated drought, but led to severe flooding in southern and central Texas in early July with damage estimates reported as high as $1 billion. Strong thunderstorms also brought widespread flooding to western Minnesota and North Dakota and resulted in hundreds of millions of dollars in damage and crop losses in June.

The combination of generally warmer- and drier-than-average conditions in other parts of the United States led to persistent or worsening drought throughout much of the country. Although there was some drought relief in the Northeast during the spring and early summer, a return to below-average rainfall during July and August led to worsening drought there. In parts of the Southeast and the West, the current drought began as early as 1998. Conditions during the past 12 months continued to be remarkably dry in many areas. Six states (North Carolina, Virginia, Colorado, Utah, Arizona and Nevada) had their driest September through August (previous 12 months) since 1895, and five states (South Carolina, Georgia, Maryland, Delaware and Wyoming) had their second driest such 12-month period in the 108-year period of record.

Moderate to extreme drought covered more than 45 percent of the contiguous United States during each of the past three months based on the Palmer Drought Index, a widely used measure of drought. The Palmer Drought Index uses numerical values derived from weather and climate data to classify moisture conditions throughout the contiguous United States and includes drought categories on a scale from mild to moderate, severe and extreme.

The most extensive national drought coverage during the past 100 years (the period of instrumental record) occurred in July 1934 when 80 percent of the contiguous United States was in moderate to extreme drought. Although the current drought and others of the 20th century have been widespread and of lengthy duration, tree ring records indicate that more severe and longer-lasting droughts have occurred in parts of the United States during the past 500 years. The severity of the 1930s drought was likely surpassed by the drought in the 1570s and 1580s over much of the western U.S. and northern Mexico, which lasted several decades in parts of the southwestern U.S.

Although the total costs of this year’s drought are not presently known, the drought diminished water supplies that led to the need for water restrictions in many cities, and contributed to an active wildfire season and extremely difficult farming conditions. More than 50 percent of range and pastures were classified as poor to very poor in 24 states by the U.S. Department of Agriculture in early September. Although production for some major crops will be lower than in recent years, some of the most productive areas of the nation’s corn and soybean growing regions have not been affected by this year’s drought.

NOAA’s Moisture Stress Index (MSI) provides historical perspective on conditions that are closely associated with national corn and soybean yields by measuring the percent of average crop productivity affected by drought (and catastrophic wetness) in the nation’s nonirrigated corn and soybean growing regions. Although this index does not include all possible weather-related conditions that can affect crop yield and production, lower MSI values reflect soil moisture conditions that are generally conducive to higher national yields while high MSI values indicate less favorable soil moisture conditions during critical phases of crop development.

The 2002 MSI showed that just over 17 percent of the average productivity for both corn and soybean crops was affected by severe drought (or catastrophic wetness) in 2002. The values, which are slightly higher than those recorded in 1999, are the highest since the mid-1990's and are indicative of less favorable growing conditions in 2002. However, MSI values in 1988 and 1983 indicate that 40 to 50 percent of the average productivity of these crops was affected by drought. In those years, severe drought covered more of the primary corn and soybean growing regions than in 2002. The 2002 MSI values were also much lower than those during the Dust Bowl years of the 1930's, when much of the nation’s agriculture was devastated by years of warmer- and drier-than-normal conditions. The U.S. Department of Agriculture estimates that the average yield in 2002 will be 9.3 percent lower for corn and 6.6 percent lower for soybean than in 2001.

The average global temperature for combined land and ocean surfaces during the June-August 2002 season (based on preliminary data) was 0.8 degrees F (0.5 C) above the 1880-2001 long-term mean, the third-warmest June-August since 1880 (the beginning of reliable instrumental records). The land-surface temperature average was also the third warmest on record (1.2 degrees F above average), while the global ocean-surface temperature was the fourth warmest on record, at 0.7 degrees F (0.4 C) above average. The June-August land and ocean temperature was slightly cooler than in 2001 and 0.3 degrees F less than the record warmth recorded in 1998.

The season was marked by numerous extreme weather events throughout the world. More than 100 people were killed across Europe as heavy and persistent rainfall led to devastating floods in the Czech Republic, Germany, Austria, Slovakia, Russia and Romania. Monsoon rains also led to hundreds of deaths in northeastern India and Bangladesh, and heavy rainfall brought severe flooding to central China. This contrasts sharply with widespread and severe drought that persisted in other parts of India and China as well as much of North America and New South Wales Australia.

NOAA’s National Environmental Satellite, Data, and Information Service (NOAA Satellite and Information Service) is the nation’s primary source of space-based and surface-based meteorological and climate data. NOAA Satellite and Information Service operates the nation's environmental satellites, which are used for weather forecasting, climate monitoring and other environmental applications such as fire detection, ozone monitoring and sea surface temperature measurements.

NOAA Satellite and Information Service also operates three data centers, which house global data bases in climatology, oceanography, solid earth geophysics, marine geology and geophysics, solar-terrestrial physics, and paleoclimatology.

Relevant Web Sites
Climate of 2002 — August and Boreal Summer in Historical Perspective

NOAA’ National Climatic Data Center

NOAA's Drought Information Center

Media Contacts:
Patricia Viets, NOAA Satellite and Information Service, (301) 457-5005 or Kent Laborde, NOAA, (202) 482-6090