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CONTACT: Patricia Viets, NOAA FOR IMMEDIATE RELEASE (301) 457-5005 January 15, 2001 Frost Days Decreasing in United States, NOAA Reports The United States as a whole has experienced a slight decrease in the number of frost days, Dave Easterling, a climatologist with NOAA's National Climatic Data Center, told scientists at the annual meeting of the American Meteorological Society in Albuquerque, N.M., today. Frost days, or the days when the minimum daily temperature dips below freezing, declined over the period 1948-1999, with the largest decreases in the winter and the spring. Easterling studied two questions for the 52-year period: Are there changes in the number of frost days per year or season? Are there changes in the dates of the first autumn frost, last spring frost, and length of the frost-free season? Changes in frost dates for autumn show little change, but the date of the last spring freeze shows a significant move to an earlier date. This results in an increase in the frost-free season. Easterling also found that there is a distinct spatial pattern to the results that is consistent with the spatial pattern of annual temperature trends for the 20th century. This patterns shows the western United States with the largest decreases in frost days, and increases in the length of the frost-free season. But the southeastern United States, which is one of the few areas of the world showing cooling over the 20th century, has no significant changes in the numbers of frost days or the frost-free season. NOAA's National Climatic Data Center, in Asheville, N.C., is the world's largest active archive of weather and climate data. The center has more than 150 years of data on hand. This includes satellite weather images back to 1960, with 55 gigabytes of new information added each day--equivalent to 18 million pages a day. Data are received from a wide variety of sources, including satellites, radar, remote sensing systems, cooperative observers, aircraft, ships, radiosonde, wind profiler, rocketsonde, solar radiation networks, and National Weather Service Forecast/Warnings/Analyses Products. NCDC supports many forms of data and information dissemination such as paper copies of original records, publications, atlases, computer printouts, microfiche, microfilm, movie loops, photographs, magnetic tape, floppy disks, CD-ROM, electronic mail, on-line dial-up, telephone, facsimile and personal visit. For more information on NCDC, see: http://www.ncdc.noaa.gov 
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Last modified: Wednesday, 19-Sep-2007 13:46:56 UTC
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