Northeast, Southwest warming fastest in U.S.

WASHINGTON – The United States is warming fastest at two of its corners, in the Northeast and the Southwest, an analysis of federal temperature records shows.

Northeastern states – led by Maine and Vermont – have gotten the hottest in the past 30 years in annual temperature, gaining 2.5 degrees on average. But Southwestern states have heated up the most in the hottest months: The average New Mexico summer is 3.4 degrees warmer now than in 1984; in Texas, the dog days are 2.8 degrees hotter.

The contiguous United States’ annual average temperature has warmed by 1.2 degrees since 1984, with summers getting 1.6 degrees hotter. But that doesn’t really tell you how hot it’s gotten for most Americans. While man-made greenhouse gases warm the world as a whole, weather is supremely local. Some areas have gotten hotter than others because of atmospheric factors and randomness, climate scientists say.

“In the United States, it isn’t warming equally,” said Kelly Redmond, climatologist at the Western Regional Climate Center in Reno, Nevada. “Be careful about extrapolating from your own backyard to the globe.”

For example, while people in the East and Midwest were complaining about a cold winter this year, Redmond’s Nevada and neighboring California were having some of their warmest winters ever.

To determine what parts of the country have warmed the most, the Associated Press analyzed National Climatic Data Center temperature trends in the lower 48 states, 192 cities and 344 smaller regions within the states. Climate scientists suggested 1984 as a starting date because 30 years is a commonly used time period and 1984, which had an average temperature, is not a cherry-picked year to skew a trend either way. The trend was calculated by the NCDC using the least squares regression method, which is a standard statistical tool.

All but one of the lower 48 states have warmed since 1984. North Dakota is the lone outlier, and cooled slightly. Ten states – Maine, Vermont, New Jersey, Massachusetts, New Hampshire, Rhode Island, Delaware, New Mexico, Connecticut and New York – have gotten at least 2 degrees warmer in the past 30 years.