September Heat Worsens Droughts across the United States

How hot was it in the U.S. this September? Hot enough to break record highs at 1,000 different locations across the country, according to news from the National Oceanic and Atmospheric Administration (NOAA).

The nationwide heat aggravated already existing droughts, spreading extremely dry conditions to almost half of the lower 48 states, according to NOAA. The areas suffering most from ongoing drought were the Southeast -- where more than three-fourths of the region was affected -- the Mid-Atlantic states and the Tennessee Valley.

"Based on the Palmer Drought Index, severe to extreme drought affected about 28 percent of the contiguous United States as of the end of September 2007, an increase of about 1 percent compared to last month," NOAA stated. "About 43 percent of the contiguous U.S. fell in the moderate to extreme drought categories at the end of September."

On the other hand, about 12 percent of the contiguous U.S. saw severely or extremely wet conditions in September, NOAA added.

In all, last month was notable for a number of records, NOAA stated. It was the eighth warmest September on record in the U.S. It saw the fifth warmest global surface temperatures on record. It marked the point at which Arctic Sea ice shrank to its lowest extent ever measured -- 1.65 million square miles, 23 percent less than the previous record set in 2005. And it was the second warmest month for global ocean surface temperatures since records started in 1880.

During September, 38 of the 48 contiguous states saw warmer than average temperatures, and none were cooler than average. Alaska recorded its 12th warmest September, with temperatures an average of 2.6 degrees Fahrenheit above the 1971 to 2000 mean. And the city of Nome was frost-free from June through the end of September; it was the second-longest frost-free season for the city in more than 100 years, being surpassed only by the record frost-free season of 1989.

Continued drought conditions and warm temperatures also brought water levels in Lake Superior to a record low for that time of year, according to NOAA's Great Lakes Environmental Research Laboratory. Meanwhile, Lake Huron and Lake Michigan both have water levels about 2 feet below average. Lake Ontario and Lake Erie were also lower than normal, by about 7 inches and a few inches, respectively.

Water levels in all the Great Lakes have been dropping since the late 1990s, according to NOAA. The Great Lakes hold about one-fifth of the Earth's fresh water.

National Oceanic and Atmospheric Administration, "September 2007 is Eighth Warmest on Record for Contiguous United States: Drought Worsens Across Southeast and Tennessee Valley." URL: (http://www.noaanews.noaa.gov/stories2007/20071016_ncdcseptwrapup.html)