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NOAA image of USA weather extremes.Oct. 17, 2003 — Many states from the Central Plains to the Southeast were cooler than average while some western states had near-record warmth last month. It all added up to a near average September for the U.S., according to scientists at the NOAA National Climatic Data Center in Asheville, N.C. The mid-Atlantic and Northeast were unusually wet, but precipitation was near average for the nation as a whole. The global average temperature was the warmest on record for the month.

NOAA scientists report that the average temperature for the contiguous United States in September (based on preliminary data) was 65.4 degrees F (18.6 degrees C), which was 0.1 degree F (0.05 degrees C) below the 1895-2003 mean. The mean temperature in four states (Maine, Vermont, Nevada and California) was much above average, while 14 other states were significantly warmer than average. Conversely, significantly cooler than average temperatures occurred in 17 states, primarily in the Central and Southern Plains, the central Mississippi Valley, the Ohio Valley and parts of the Southeast. The average September temperature in Alaska was 1.1 degrees F (0.6 degrees C) below the 1971-2000 mean.

Overall, precipitation for the contiguous U.S. was near average, but the western U.S. was drier than average, while much wetter than average conditions stretched from the Mississippi Valley to the mid-Atlantic and Northeast. Much of the monthly rainfall in states from North Carolina to Maine was attributable to Hurricane Isabel, which made landfall along the Outer Banks of North Carolina on Sept. 18.

Hurricane Isabel moved over areas that had been persistently wet for the last 12 months. Virginia had its wettest October-September on record with rainfall exceeding the next wettest October-September by a remarkable 10 inches (254 mm). More than 65 inches (1650 mm) fell from October 2002 to September 2003. This rainfall total is also remarkable for the fact that it was over twice the amount that fell during the previous 12-month period (32.1 inches from October 2001 through September 2002), the third driest October-September period on record. Three other states had their wettest such12 months on record (Delaware, Maryland and North Carolina), and the Southeast as a whole was the wettest in 108 years of record keeping for that 12-month period.

In contrast to the record and near-record rainfall in the East, drought continued to affect many parts of the West. While some improvement occurred early in 2003, drought severity worsened in the succeeding months. At the end of September 2003, 76 percent of the western United States was in moderate-to-extreme drought, based on a widely used measure of drought, the Palmer Drought Index, and drought also persisted in the Plains and Upper Midwest. The most extensive drought on record for the West occurred in July 1934, when 97 percent of the region was in moderate-to- extreme drought.

The average global surface temperature for combined land and ocean surfaces during September 2003 (based on preliminary data) was 1.0 degree F (0.6 degrees C) above the 1880-2002 long-term mean, the warmest September since 1880 (the beginning of reliable instrumental records). The second and third warmest on record occurred in 1997 and 1998, respectively. Since 1900, global surface temperatures have risen at a rate of 1.0 degree F/century (0.6 degrees C/century), but the rate has increased to approximately three times the century-scale trend since 1976.

Land surface temperatures were the second warmest for September. Temperatures were extremely warm throughout much of eastern Canada, where monthly anomalies in excess of 4.0 degrees F (2.2 degrees C) were widespread. Unusually warm temperatures also covered much of Asia and Europe. The global ocean surface temperature was warmest on record, although temperatures in much of the central and eastern equatorial Pacific were near the 1971-2000 average as the neutral phase of ENSO (El Nino/Southern Oscillation) continued.

The NOAA Environmental Satellites, Data and Information Service is the nation’s primary source of space-based meteorological and climate data. It 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.

The NOAA Environmental Satellites, Data 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.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nationís coastal and marine resources. NOAA is part of the U.S. Department of Commerce.

Relevant Web Sites
Climate of 2003 — September in Historical Perspective

NOAA National Climatic Data Center

Media Contact:
John Leslie, NOAA Satellites and Information Service, (301) 457-5005