CHICAGO (AP) _ Arctic temperatures in the nation's midsection are boosting last-minute holiday travel during the peak Christmas and New Year's season, and airlines have aided the cold-weather flight by lifting advance-purchase requirements, travel agents said Monday.

A trend to shorter vacations that can be booked with short notice has been encouraged by the recent cold weather that has frozen much of the country.

''People are saying, 'Hey, it's 7 degrees in Chicago, let's get out of here for a few days,'' said Greg DeClemente, vice president for leisure travel at Thomas Cook Travel in New York.

Last-minute customers at Windy City Travel Inc. in Chicago want to go ''anywhere that's warm and they don't seem to care where,'' said Cliff Stern, company president.

''Snow and cold is a godsend to travel agents. The phones ring off the hook,'' Stern said.

Temperatures Monday morning were below zero in the Upper Plains, in the teens in the Rockies and in the 20s along the Texas Panhandle.

Record low temperatures, ranging from minus 3 degrees to minus 10 degrees, were recorded over the weekend in Cleveland, Columbus, Ohio, Elkins, W.Va., Paducah, Ky., and Indianapolis.

A number of airlines, under pressure to increase fares because of recent cost increases, said two weeks ago that they were raising the prices on their popular deeply discounted fares, commonly known as MaxSavers. But many airlines also announced they would waive the 14-day advance-purchase requirement between Dec. 20 and Jan. 5, subject to seat availability.

Stern said that in some instances, airlines are adding discounted seats that can be purchased on short notice and are close to the cost of the MaxSavers.

''The holiday season has been shaping up pretty well,'' said Jurgen Krenzien, president of Paul Klein Travel Service Inc., in Chicago.

''The problem we have had is that people this year more so than in the past have decided in the last minute to do something.''

The last-minute rushes mean it may be difficult to coordinate plane flights and hotel reservations, Krenzien said.

But some agents said the availability of discounted seats during the holiday - when the deepest discounts are normally blacked out - means the airlines have too many empty seats.

Good prices mean air travel is down, said Susan Storb, general manager of the vacation division for Rosenbluth Travel Agency Inc., in Philadelphia.

''I just think it's just not as strong as it's been over the past few years,'' she said.

Strong bookings for January through March indicate people are postponing discretionary travel, Ms. Storb said.

''People are looking for good value, and it can be expensive over the holidays,'' she said.

In Los Angeles, where people don't have to flee the balmy weather, the travel business is holding its own for the holiday period, said Susan Kaplan, president of the Southern California chapter of the American Society of Travel Agents.

A general feeling that the economy is on a ''normal'' course may be contributing to a slight increase in travel bookings, Ms. Kaplan said.

Things are not as rosy for some hotels in California.

Fred Gholi, manager of the Sunset Plaza Hotel in Los Angeles, said he doesn't expect to be more than 70 percent full during the holidays.

''Compared with last year, it's terrible,'' he said.