http://www.usatoday.com/weather/climate/2007-01-09-warmest-year_x.htm
TOP 10 WARMEST YEARS IN U.S. HISTORY
Rank Year Average temperature (F)
1. 2006 55.01
2. 1998 54.94
3. 1934 54.91
4. 1999 54.53
5. 1921 54.49
6. 1931 54.34
7. 1990 54.24
8. 2001 54.23
9. 1953 54.18
10. 1954 54.13
Source: National Climatic Data Center
By Patrick O'Driscoll, USA TODAY
DENVER ? Last summer's deadly heat wave and a balmy December helped make 2006 the warmest year ever recorded in the USA, federal climate officials announced Tuesday.
The National Climatic Data Center says factors include the El Ni?o climate pattern and "the long-term warming trend" of climate change, due in part to greenhouse gases. The center says drought in the Plains and parts of the West also played a role. Wildfire agencies say warmth helped make it the worst wildfire season ever, with 9.8 million acres burned.
"There's no denying that climate change is occurring, and warmer winters and warmer years are more common for that reason," says Jay Lawrimore, monitoring chief for the center, which keeps the nation's weather records. "What we're seeing (in 2006) is just becoming so much more common."
New York City, still without snow this winter, last week broke a 129-year record for latest date for the first snowfall. In the Northeast, ski resorts report little snow and temperatures too warm to make artificial snow.
Temperatures were above normal even in Colorado, where major snowstorms before Christmas and New Year's paralyzed Denver and socked the Great Plains. The city's average reading for December was still 1.4 degrees warmer than usual.
A side benefit: Residential energy demand for heating was 13.5% lower than normal for October through December, the center said.
An average national temperature of 55.01 degrees pushed 2006 past 1998 as the warmest on record. Fifteen of the years since 1981 rank among the 25 warmest since national record-keeping began in 1895.
The climate center says the current El Ni?o, the periodic warming of Pacific waters, is the biggest factor for 2006, and global warming is "a contributing factor." This is believed to be the first time the annual temperature report mentions climate change as a cause.
It was the warmest year ever in New Jersey, and five states had their warmest December ? Connecticut, Minnesota, New Hampshire, New York and Vermont.
During last summer's heat wave, record highs from South Dakota across the Plains taxed water supplies for crops and livestock. Heat was blamed for at least 140 deaths in California.
The year's warmth wasn't just about extreme highs. Lawrimore says more than 40% of the USA had higher-than-average overnight lows last summer, compared with 10% in a typical year. Daily records for the highest overnight low were tied or broken more than 3,000 times last summer in hundreds of cities and towns, especially in the West. About 100 locations recorded their all-time highest lows for any date, from 88 in Cedar Butte, S.D., to 102 in Death Valley, Calif.