The December 2006-February 2007 winter season temperature was marked by periods of unusually warm and cold conditions in the U.S., but the overall seasonal temperature was near average, according to scientists at NOAA's National Climatic Data Center in Asheville, N.C. Precipitation was above average in much of the center of the nation while large parts of the East, Southeast, and Southwest were drier than average. The global temperature was the warmest on record for the December-February three-month period.

U.S. Temperature Highlights

The winter temperature for the contiguous United States (based on preliminary data) was 0.6°F (0.3°C) above the 20th century average of 33.0°F (0.6°C). Statewide temperatures were warmer than average from Florida to Maine and from Michigan to Montana. Cooler than average temperatures occurred in the southern Plains and areas of the Southwest.

The winter season got off to a late start in much of the country. December was the 11th warmest such month on record (based on revised data), and spring-like temperatures covered much of the eastern half of the nation during the first half of January.

Upper level wind patterns brought unusually cold weather to the southern Plains and much of the West in January and snow and ice extended as far south as Arizona, southern California, and south Texas. More typical winter conditions finally arrived in the eastern U.S. by late January and a period of colder than normal temperatures persisted through Presidents Day weekend.

February as a whole was 1.8°F (0.9°C) below the 20th century average of 34.7°F (1.5°C), colder than two-thirds of the Februarys in the 113-year record for the contiguous U.S. Thirty-six states in the eastern two-thirds of the nation were cooler than average, while Texas and the eleven states of the West were near average to warmer than average.

The warmer-than-average seasonal temperatures in the more heavily populated regions of the Midwest and East helped reduce residential energy needs for the nation as a whole for the winter season. Using the Residential Energy Demand Temperature Index (REDTI - an index developed at NOAA to relate energy usage to climate), NOAA scientists determined that the nation's residential energy demand was approximately 3 percent lower than what would have occurred under average climate conditions for the season.

Seasonal energy demand would have been lower if not for February's colder temperatures. For the month, temperature-related residential energy demand was approximately 6 percent higher than what would have occurred under average climate conditions for February.

For the state of Alaska both February (1.4°F/0.8°C) and winter (1.6°F/0.9°C) were warmer than average, but far from the record warmth of 2003 and 2001, respectively.

U.S. Precipitation Highlights

Winter season precipitation was above average in the central U.S. from the Upper Midwest to New Mexico, Texas and Louisiana. Drier-than-average conditions stretched from the Deep South to Kentucky, the Mid-Atlantic, and along the Northeast Seaboard states. Much of the West was also drier than average. Through early March, water-year precipitation in Los Angeles was the lowest on record, less than 25% of normal.

Several snow storms hit the Plains, Midwest, and Northeast in February. A complex, wide-reaching winter storm moved from the Mid-Mississippi Valley into the Mid-Atlantic and New England February 14 and 15. The heaviest snow fell in interior regions of the Northeast where amounts over 20 inches were widespread. This event was preceded by a 10-day lake effect storm that dumped more than 100 inches of snow on New York's Tug Hill Plateau. A total of 141 inches was reported at Redfield in Oswego County.

Two winter storms coming within a week struck the Upper Midwest in late February and early March. Heavy snowfall with record-breaking amounts in some locations occurred from February 23 through March 2. An all-time single storm record of 21 inches occurred in La Cross, Wisconsin during the first storm and the second storm helped set a new record for the most snowfall in a 7-day period (27.4 inches).

Beneficial snows fell in the Sierras of California and the Great Basin Ranges in late February and early March, but the winter as a whole remained much drier than average. For all but the Northern Cascades and the Front Range of the Rockies in Colorado and New Mexico, seasonal snowpack was below average in early March. Spring and summer snow melt is a major source of water for the West, and the lack of abundant snowpack in the mountains of the West can lead to water supply problems later in the year.

For February, precipitation was below average in the Southeast, Northeast, and Midwest regions. For the Southern Region, the 9th driest February on record followed two wetter-than-average months.

According to the U.S. Drought Monitor, 25 percent of the continental U.S. was in moderate to exceptional drought at the end of February, approximately 5% less than the same time last year. The most severe drought conditions were present in southwest Texas, northern Minnesota, Wyoming and the western High Plains.

Global Highlights

The global land and ocean surface temperature was the 6th warmest on record in February, but a record warm January helped push the boreal winter (December-February) to its highest value since records began in 1880 (1.30°F/0.72°C above the 20th century mean). The presence of El Niño conditions contributed to the season's record warmth, but the episode rapidly weakened in February as ocean temperatures in the central equatorial Pacific cooled more than 0.5°F/0.3°C and were near average for the month.

Separately, the global December-February land-surface temperature was the warmest on record while the ocean-surface temperature tied for second warmest in the 128-year period of record, approximately 0.1°F (0.06°C) cooler than the record established during the very strong El Niño episode of 1997-1998.

During the past century, global surface temperatures have increased at a rate near 0.11°F (0.06°C) per decade, but the rate of increase has been three times larger since 1976, or 0.32°F (0.18°C) per decade, with some of the largest temperature increases occurring in the high latitudes of the Northern Hemisphere.