Thursday, January 6, 2011

U.S. December Cold Records Exceed Heat Records

For related record temperature posts, see:
For the first time in 2010 since February, the December number of daily record low temperatures in the U.S. exceeded the number of record highs. The excess of cold records, however, barely made a dent in the cumulative excess of heat records which had built up to more than 7200 over the spring, summer, and fall. The cumulative excess finished the year 2010 at a little under 7000.

The monthly total of 1052 daily record low minimums also barely exceeded the 903 record high minimums. Both cold and heat records were far exceeded by the over 2500 daily precipitation records.

After reaching a level of over 4:1 in each of April, June, September, and October, the ratio of heat records to cold records was 2.28:1 for the year 2010 overall.

The daily record count shows that the cold extremes were not consistent through the month. They were centered around 3 sharp Arctic outbreaks peaking on the 8th (120 records), 15th (154 records), and 28th (155 records). Heat records dominated strongly during the week ending on Christmas, when a total of only 3 cold records were reported, vs. 207 heat records.

For the entire year 2010, preliminary surface temperature data from NCEP/NOAA show that most of the U.S. averaged near or above the climatological mean, except for the southeast coast and Florida.

Images (click to enlarge):
- Monthly total number of daily high temperature, low temperature, and high minimum temperature records set in the U.S. for July through December 2010, data from NOAA National Climatic Data Center, background image © Kevin Ambrose ( Includes historical daily observations archived in NCDC's Cooperative Summary of the Day data set and preliminary reports from Cooperative Observers and First Order National Weather Service stations. All stations have a Period of Record of at least 30 years.
- Cumulative excess of heat records vs. cold records by month for 2010, data source as above
- High temperature, low temperature, and precipitation records set in the U.S. for December 2010, data source as above
- Daily numbers of high and low temperature records set in the U.S. for December 2010, data source as above
- 2010 annual temperature departure from climatological average from NOAA/NCEP via ESRL

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