National Climatic Data Center, 15 May 2003

April Temperatures

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The graph to the left shows monthly mean temperature averaged across the contiguous United States based on long-term data from the U.S. Historical Climatology Network (USHCN). The value for 2003 is estimated from preliminary Climate Division data using the first difference approach. April 2003 ranked as the 38th warmest April in the 1895 to present record. The preliminary nationally averaged temperature was 52.7°F (11.5°C) which was 0.6°F (0.3°C) above the long-term mean.

The center of the U.S. was generally warmer than average in April 2003 with 18 states ranking in the above average temperature category. However, parts of the Northeast and west coast were cooler than normal for April. Maine and California ranked as 3rd and 10th coldest on record for the month respectively. As can be seen in a map of divisional temperature (below right), significantly warmer than average temperatures occurred in divisions in Colorado, Wyoming and Ohio. Overall, however, April was not a month with many temperature extremes. The pattern of warmth and cold in the contiguous U.S. in April broadly corresponded with the mean 500mb height and anomalies chart. This shows that above normal 500mb heights extended across the central portion of the U.S., and into the Northeast. These were associated with the above average temperatures across the mid-section of the country, though the cool surface temperatures in the Northeast for April corresponded more to the trough in eastern and southeastern Candada. Below average 500mb heights existed across the western portion of the United States leading to the lower monthly average temperatures there. It was the 10th warmest April since reliable statewide records began in 1918 for Alaska , with anomalies of 3.4°F (1.9°C) above normal relative to the period 1971-2000.

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Temperature Departures

A new April minimum daily temperature record was set in Negaunee Township, MI on April 6th when the low reached -9°F (-22.8°C) and on April 9th a new record low maximum temperature of 46°F (7.8°C) was set in Jackson MS, breaking the old record of 47°F (8.3°C) set on April 12th, 1940. Numerous daily maximum temperature records were broken in April in Alaska and also in the northern Great Plains. A maximum temperature of 90°F (32.2°C) was reached in Bismarck, ND on April 13th. This is the earliest date that 90°F has been reached in Bismarck. The previous record was 92°F (33.3°C) on April 18th, 1987. At least two locations in Alaska set new all-time high temperature records for the month of April on April 26th - 76°F (24.4°C) was reached in Skagway, and maximum temperatures were 74°F (23.3°C) in Juneau.

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February - April 2003

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The graph to the left shows mean temperature averaged across the contiguous United States based on long-term data from the U.S. Historical Climatology Network (USHCN). The value for February-April 2003 is estimated from preliminary Climate Division data using the first difference approach. February to April 2003 was marginally warmer than average and ranked as the 46th warmest such period in the 1895 to present record. The preliminary nationally averaged temperature for February-April was 43.3°F (6.3°C) which was 0.3°F (0.2° C) above the long-term mean.

Twelve states averaged warmer than the long-term mean from February-April, and four Northeastern states were colder than average. Maine ranked as 8th coldest on record for the 3-month period, falling in the much colder than average category.

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National Temperatures - May 2002-April 2003

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The graph to the left shows mean temperature averaged across the contiguous United States based on long-term data from the U.S. Historical Climatology Network (USHCN). May 2002-April 2003 ranked as the 17th warmest such period in the 1895 to present record. The preliminary nationally averaged temperature was 53.5°F (11.9°C) which was 0.7°F (0.4°C) above the long-term mean.

The western half of the contiguous U.S. was generally anomalously warm over the May 2002-April 2003 period with six states averaging much above normal. A further eight states were significantly above average temperature for the twelve months. The eastern U.S. was cooler with most states averaging near normal. Seven states were significantly cooler than normal and Maine ranked as 9th coldest May-April since 1895.

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Questions?

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