It was one of those Christmas seasons when Santa Claus kept his signals straight but the weather elves weren't so consistent. Sharp contrasts in weather cross the nation during the four-day holiday weekend brought smiles to some and tragedy to others.

Children in Denver set aside their shiny new skates and sleds yesterday and went outdoors to play football in their shirtsleeves, while in Charleston, S.C., four inches of new snow blanketed the ground and motorists skidded along ice-glazed roads.

Heavy rains in the Pacific Northwest, added to unseasonably warm temperatures that melted snow in the moutains, sent streams out of their banks and forced hundreds out of their homes in low-lying areas. A 100-mile-an-hour chinook wind blowing down from the mountains had the temperature in western Montana up to record levels by 5 a.m. yesterday.

Southern Californians flocked to beaches to escape record high temperatures in the upper 80s, while the Northeast suffered through its fourth day of subfreezing weather after a Christmas Eve cold snap sent the mercury plummeting to record lows from Maine to Maryland.

The law of averages would indicate that the weather must be perfect somewhere in the middle, and sure it was 70 degrees under blue skies in Kansas.

The weather extremes on the East and West coasts were expected to moderate by today, according to a spokesman for the National Severe Storms Forecast Center in Kansas City, Mo., which keeps track of the weather across the nation, but flooding will continue to be a problem in the Northwest for several days, and the Midwest and East Coast, including the Washington area, can expect cold weather with snow flurries through New Year's Day.

The mixed bag of weather, the spokesman said, was caused by several air patterns:

In the Northeast and northern Midwest, an Arctic air mass moved down from Canada across countryside lightly blanketed with snow. The result was not just mere cold but frigid cold, with temperatures on Christmas Day as low as 26 degrees below zero in Maine.

The same air mass ambled down the East Coast. When it got to southern Virginia yesterday, it hit moist air coming from an Atlantic storm system centered off shore. The result was freezing rain, sleet and snow as far south as southern Georgia.

The bitter cold was blamed for at least 10 deaths from Connecticut to North Carolina, including a Chicago man found dead in a snowbank Christmas Day and a Georgia motorist whose car slid off an icy bridge.

Meanwhile, a high pressure system snuggled against the western side of the Bitterroot and Sierra Nevada mountain ranges in the West, warming things up in Southern California while it dropped rain in western Oregon and Washington, northern Idaho and eastern Montana. Rivers and streams spilled out of their banks and sodden hillsides collapsed into mudslides, destroying bridges and summer cottages. A Parkdale, Ore., man died when floodwaters swept away his mobile home, and a woman in western Oregon died when her car hit mudslide debris.

The rain diminished yesterday, but rivers were still at flood stage. In Liberty, Mont., volunteers put up 10,000 sand bags to save homes near flooding creeds, and in northern Idaho, the Coeur d'Alene River was 6 1/2 feet above flood stage.

A Pacific front was bringing the temperature down a bit in California yesterday, but the cooler, moist air also shrouded the coastline in fog from one end of the state to the other. Three San Francisco area airports were closed for nearly seven hours yesterday morning, and Los Angeles also reported fog problems.

Cold air sweeping down the eastern slopes of the Rocky Mountains warmed and built up speed as it descended, turning into the hot, dry chinooks that can raise the temperature on the plains 40 degrees in a matter of minutes. Record highs in the 60s were set in Helena and Great Falls, Mont., before dawn yesterday morning, and Denver basked in sunny weather in the high 60s by daybreak. The winds, gusting up to 100 miles an hour across the flatlands, pushed balmy weather across eastern Colorado into western Kansas.

There was little rejoicing over the unusual weather in the ski lodges of the Sierra Nevadas, where the heat mealted what little snow was on the ground, or in the eastern Rockies, where resort operators were forced to augment their snow base with manmade flakes.

A meteorologist in Denver was hard put to say when that situation might change. "Only the good Lord knows," he said in his best inexact-science style. But, like many Denverites, he was not about to look his gift weather in the isobar: "I don't care if I ever see a flake of snow."