The sweltering month of August was "the hottest August on record, even topping record Dust Bowl years," the National Weather Service announced yesterday.

The month was "probably the hottest of this century," though complete records date back only to 1931, the nation's meteorologists said.

The average temperature for August was more than 4 degrees above normal in more than half the country.

The summer was the 17th hottest on record for the United States as a whole.

Temperatures were especially high in the East and Midwest.

"The combination of heat and drought was most severe in the central Mississippi valley in an area extending from Kansas and Nebraska eastward into Indiana and Kentucky, and in a belt along the East Coast from the Carolinas to New Jersey," the weather service said.

Some cities, including Washington, have had a few hotter Augusts. The average temperature this August was 81, the third highest in records dating back to 1871. Only August 1980, when the average temperature was 82.8, and August 1978, when it was 81.3, were hotter.

The averages are day-and-night averages.

Washington had 20 days of temperatures 90 degrees or above, and reached 101 on Aug. 20.

Nationally, city after city--especially in the Midwest and, almost equally, in the Southeast--set temperature records. Fayetteville, N.C., and Grand Island, Neb., suffered all-time highs of 110 degrees.

People and crops wilted. And "the year's heat and drought," which developed in mid-July and has continued into September, "claimed at least 220 lives and withered 0 million worth of crops," the weather service said.

The blame for it all belongs to a misguided set of "westerlies," the winds that carry weather from west to east across the North American continent, according to Don Gilman of the service's Climate Analysis Center.

The westerlies include the jet stream, the high-speed core of the westerly winds, which flows five to eight miles above the ground. But they also include winds only a few miles up.

Most typically, said Gilman, westerlies pursue a summer track along the Canadian border. This year they were drawn much farther north, into the Arctic.

The reason for the shift remains unknown. El Nino, the warm Pacific current off South America that heated up trade winds, was probably not the cause of this country's summer sweltering and drought, Gilman said, though El Nino pelted California with winter storms and floods, and caused severe weather and drought worldwide.

The summer's northward shift of the North American westerlies meant "very few cold fronts or storm tracks penetrated into the United States," Gilman said. And after a cool June, the torrid "pattern became marked in the second half of July, dominated all of August and was still in place to a fair extent in the first half of September, although weakening."

The lack of stormy or cool air "allowed a lot of solar heating under rather clear skies . . . a very stable pattern" that allowed summer to do its worst, Gilman said.

Though the temperature has been hitting the 90s again this week in the East, the picture is changing, the weather service said. There is currently cool weather over much of the country and early snow in the Rockies.

The mid-September to mid- October outlook calls for a 55 to 60 percent chance of below-normal temperatures in most Eastern and Midwestern states, with warmer than normal temperatures only along the West Coast, the Mexican border and southern Florida.

"What we're getting" in Washington and the East "are a series of flip-flops, alternating hot and cold weather," Gilman said. "But there's some really cold weather coming across the country now. I don't know whether it will come crashing through to the East Coast or not, but we should be having more and more cooler days."