The Washington area, which handily managed its slushy snow yesterday, is now braced for a bitter blast from Canada that could bring the coldest weather since January 1985, when frigid temperatures drove President Reagan's second inauguration ceremonies indoors and left the city shuddering.

Though temperatures will not drop as drastically as they did then, according to forecasters, the temperature is expected to sink to 5 to 10 degrees tonight and rise only into the 20s today and Wednesday. The windchill factor could make it feel as cold as 13 below zero at night, according to the National Weather Service.

"Go outside right now," Rick Thoman, of the Accu-Weather service, suggested yesterday afternoon, "and it will be the warmest weather you'll find until the weekend."

The plummeting temperatures can create a wide variety of problems -- frozen pipes for homeowners, medical problems for the elderly, ill or those who don't take proper precautions and a potentially deadly shortage of space at the city's homeless shelters.

Much of the nation was suffering the same frigid fate, as the jet stream, which acts as the steering system for weather systems, dove south with an Arctic air mass that has been building in Canada for days, forecasters said.

The cold extended from the Rockies all the way to the East Coast and as far as the northern Gulf Coast, according to Accu-Weather's Thoman. "The only place it has not gotten to, and probably won't, is Florida," said Thoman.

In Washington yesterday, despite a snowfall that totaled 3.3 inches at National Airport, Metrorail and area highway officials reported a near-normal rush hour. Several area school systems opened one or two hours late, but only one -- Prince George's County, where school officials reported heavier snow -- closed for the day.

The next possibility of snow, according to both weather services, is Friday. "But it's hard to tell this far out," said Thoman. He said the potential comes from a strong storm that caused flooding in Hawaii on New Year's Eve and is now a few hundred miles off the California coast.

Yesterday's snow, which began falling shortly after 5 p.m. Sunday and ended about 12 hours later, got the snowplows onto the roads throughout the area and caused the District and Maryland suburbs to declare a snow emergency.

With that declaration, the city's Department of Public Works and D.C. police took to the snow emergency routes, where they ticketed 1,300 vehicles and towed 500 of them to make way for plows and trucks carrying salt and sand.

Public Works Department spokesman Tara Hamilton said people reacted more quickly by moving their cars than they had for the season's first storm Nov. 11, when a foot of snow fell. "It seems the message has gotten across," said Hamilton, who said the quick reaction time made the cleanup easier and more complete.

Sunshine and rising temperatures, which reached 39 degrees, helped to clear the major thoroughfares, and salting and sanding continued throughout the day in most areas, officials said.

Some D.C. residential streets, however, still were covered with snow and the falling temperatures were expected to produce some hazardous ice on those streets, Hamilton said.

Nevertheless, officials expected few problems on the major roads for this morning's rush hour, despite the plummeting temperatures. Metrorail was planning to run on a regular schedule today, according to spokesman Marilyn Dicus.

Yesterday, Metrorail ran longer trains and extended its morning rush hour to accommodate higher volume and commuters who went to work later, according to Dicus. Buses on about 20 of the system's more than 700 routes were rerouted because of icy roads and hills in the District and Prince George's County in the morning. By evening rush hour, those routes were back to normal, Dicus said.

The federal government announced that a "reasonable amount of tardiness would be excused" yesterday without any use of annual leave, according to a spokesman for the Office of Personnel Management.

Several jurisdictions, including the District, delayed school openings, and Prince George's County closed all but six of its schools. Those six, which offer extended day programs, remain open even in inclement weather, spokesman Brian Porter said.

Porter said that parts of the county got the largest snowfall in the area, and officials decided that paths and parking lots could not be cleared enough to ensure the safety of students.

"Our big concern {for today} is freezing temperatures and ice," said Porter, echoing the concern of many area officials. But highway officials said some salt and sand trucks were to remain on duty at night to take care of trouble spots for the morning rush hour.