Old Man Winter continued to cower far from Washington yesterday as temperature records were broken in 42 locations around the country and temperatures here climbed into the 70s.

Record highs were reached in cities from Milwaukee to Tupelo, Miss., as much of the country luxuriated in the warm breezes of a freak December spring. At National Airport, the mercury climbed to 71 degrees, just four degrees shy of the high recorded back in 1946.

Records were set in Baltimore, at 70 degrees, Richmond, Norfolk and Lynchburg, all 76 degrees, and Roanoke, 75. According to the National Weather Service, today and Sunday will bring more of the same to the Washington area before a slight cooling early next week.

In fact, the coolest place in the Washington area yesterday may have been indoors, in the cool, white vault of the Mount Vernon skating rink in Fairfax County. This month's above-average temperatures have shut several open-air rinks around Washington, but at Mount Vernon thick walls and eight electric compressors kept the air inside a chill 50 degrees.

"I wish it would snow," sighed 12-year-old Jeffrey Hosmer as he clambered off the ice in a pair of rented skates.

Meteorologists at the National Weather Service attributed the unseasonably warm weather to an abnormal swing of jet stream air from Mexico. That created summerlike conditions in the Midwest and mid-Atlantic and winter in the Northern Plains and parts of New England.

In the Midwest, temperatures climbed into the 60s and 70s over the Ohio, Tennessee and the middle and lower Mississippi valleys and much of the Central and Southern Plains. In Iowa, almost every weather station set a record high, with Des Moines reporting a record 68 degrees. Record highs were set in Wisconsin even though there was snow on the ground.

The winter of 1984 could still be found in some places. Temperatures were at or near zero from northwest Minnesota across portions of the Northern Plains to the northern Rockies. In Wolf Creek Pass, Colo. yesterday, 26 inches of snow fell in one 24-hour period.

In New England freezing rain created chaos on many roads.

In Washington, it was springtime. A spokesman for Washington Gas Light Co., which heats two out of three area homes, said that customers could expect this December's heating bills to be as much as 10 percent below those of a year ago. "The good news is that the bills that come in in January should be significantly lower," said spokesman Tom Julia.

One man's good news is another's dirge, however. At ski resorts in Maryland and West Virginia the balmy breezes mean that even the artificial snow can't do the job.

At Wisp resort in Western Maryland only six of 16 slopes are open, and those have required double coatings of the artificial snow. It lasts only a week or two in warm weather, said Wisp operations manager Jerry Geisler. "That gets incredibly expensive."

Resorts in both states have slashed the price of lift tickets, offered discounts on lodging and even opened summer activities to lure customers.

Canaan Valley resort in Davis, W. Va., for example, has imported jugglers, magicians and disco music. The outdoor pool has been heated up and the tarps have been taken off the tennis courts. "This is traditionally a big week for us," said one sales manager, "so we've got to do something to get people out here. A resort spokesman said only two of 12 slopes were in operation.

It was certainly the weather that filled the parking lots at Mount Vernon yesterday. There were long lines for ice cream cones at the snack bar.

And tooling down Washington Street in Old Town, Alexandria was the surest warm-weather harbinger of all: a red convertible Kharman Ghia, top down.