Washington plunged into the deep freeze yesterday, its downtown sidewalks eerily emptied by an arctic blast that was expected to force temperatures down to zero tonight. By all accounts, there was no thaw in sight, and some forecasters predicted a major snowstorm Friday.

Although the worst was yet to come, Washington already looked like a city shivering through a cold wave. "It's hideous," said Julia Parry, a 23-year-old British exchange student trudging resolutely toward the Mall. "I want to go find a warm museum."

The chilling signs were everywhere. Homeless shelters throughout the metropolitan area were bursting at the seams, and the District took emergency action yesterday to open some of its public buildings to the homeless. The Potomac area AAA was registering 150 calls an hour from stranded motorists, more than twice the normal number. And the streets were peopled only by those who make their livings outside or a few hardy souls scurrying from one warm building to another.

Public health officials were warning that it is dangerously cold, and in one case, were trying to determine if the bitter chill was a factor in the death of a Northwest woman, who was found dead yesterday morning in her driveway. The D.C. medical examiner's office said that one homeless man died of exposure during the weekend and that the weather might have been a factor in yet another death last week.

The thermometer registered 27, its high point for the day at 12:01 yesterday, then started going down. A low of 14 was recorded last night. The windchill factor made it feel as if it were really about zero or below. But that was only a hint of what is to come.

Forecasts for today call for highs hovering around 20, with a windchill of 10 below zero, according to Accu-Weather's Rick Thoman. Tonight, with forecasters predicting lows of zero to 5 degrees, Washington could break its record for the date of 2 degrees, set in 1884, according to forecaster Bob Oszajca, of the National Weather Service.

The normal temperature for today, calculated over 30 years by the National Weather Service, is a high of 43 and low of 28.

Washingtonians were far from alone in their misery.

In the upper Midwest, subzero cold and blustery 30-mile-per-hour winds combined to create windchills of 75 degrees below zero in northern Minnesota and North Dakota.

In Chicago, the eerie beauty of billowing clouds of steam rising into the chilly air above Lake Michigan gave evidence of the cold. The temperature was a numbing 11 degrees below zero at daybreak and never went above zero.

The brutal, minus 54 degree windchill was capable of freezing exposed skin in minutes. At least three deaths in Chicago have been attributed on the cold.

The villain this week was an Arctic air mass that has been building in Canada for several days and was driven down across much of the nation by the jet stream. While forecasters predict that temperatures could rise to the freezing point -- 32 degrees -- on Friday, that slight warmup will be followed by more bad news.

A storm, which dumped rain on the California coast yesterday, was headed east and could arrive in the Washington area Friday, according to Accu-Weather's Thoman. "I would not want to put it in terms of numbers {of inches} this far in advance," he said. "But it has the potential to bring a healthy snowstorm to Washington."

Tara Hamilton, spokesman for the D.C. Department of Public Works, said officials "are very aware" of the potential and were readying their snow equipment and salt supplies. "Each storm is unique," she said, "and we will get ready for this one."

Meanwhile, every one from public officials to gas station operators was coping with winter's first big chill.

D.C. Public Health Commissioner Reed V. Tuckson said the medical examiner was trying to determine whether a heart attack and the cold weather were factors in the death of 68-year-old Lois Barre, who was found dead in her driveway at 1859 Redwood Ter. NW at about 8 a.m. yesterday.

The city has had its first fatality due to the cold: an unidentified homeless man believed to be about 50 years old who was found dead in the 1200 block of G St. NW Sunday morning, according to police. A medical examiner's report said the man, who was found in a booth used by parking lot attendants, died of exposure.

The office also said that exposure may have been a factor in the death of a second homeless man, John Wilks, who was found dead Dec. 31 in an abandoned car.

No deaths from exposure have been reported in the Maryland or Virginia suburbs.

The D.C. Council took emergency action to use certain public buildings as shelters when temperatures fall to 25 degrees or below. The city immediately opened the ground floor of the District Building and the Randall School building in Southwest to the homeless, although it was unclear how long those facilties would be used.

Two District shelters, the Blair and Pierce men's shelters, housed 411 persons yesterday in areas meant for 300 by providing "sit-up" space. An additional floor at homeless advocate Mitch Snyder's Community for Creative Non-Violence shelter at 2nd and D streets NW, which has been under renovation, was to be opened last night, creating space for another 300 people.

In Reston, the North County Community Shelter's 28 beds have been filled since the shelter opened two weeks ago, and workers have been scrambling to find space elsewhere. "The bottom line is we don't want anyone out there freezing to death," said director Jana Graves.

At the Bethesda Shelter, which has been housing 50 people a night on many cold nights since November, a recent fire marshal's visit has forced the shelter to limit its occupants to 30, officials said yesterday.

During the last five winters, 54 people, including 30 homeless people, have died from hypothermia in the District, according to the medical examiner's office.

Since Sunday, the city's hypothermia unit has sent out vans to pick up about 150 people off the street and take them to shelters, according to the program's director Thomas Smith. He urged people to call the unit, which operates a hot line at 727-3250, if they see someone on the street who appears to need help.

D.C. Fire officials warned yesterday that when temperatures plunge, people often try to keep warm by means that are potentially deadly. Fire Department spokesman Leo Givs said ovens should never be used for heating. He said that residents should be careful when using space heaters, fireplaces and extension cords that can be easily overloaded, and he suggested checking near furnaces for combustible materials. "The winter season presents a unique set of hazards for fires," he said.

Throughout the area, people braced for the further effects of the bone-chilling blast from the north. Several plumbing contractors said temperatures had not plunged far enough to see a rash of frozen pipes, but expected an onslaught of calls today. Service station manager Carl Lotto, of the Embassy Chevron in Northwest, said his calls were running "about 30 percent" above normal yesterday, adding that he expected "the real test" today.

A few brave souls went about their business as if freezing blasts were normal, and some even seemed to revel in the cold.

Pae Suckdoh, a Korean street vendor, did a brisk trade in wool scarves at the corner of 15th and K streets. A park ranger reported that business was fairly steady at the Washington Monument, which tourists see "as a must" no matter what the weather. And Tom Quasney, 38, joined the handful of joggers who made their way along the Mall. "Every day, no doubt about it," he said matter-of-factly.

Willard Hotel doorman George LeMay rocked from one foot to another and hailed cabs for well-dressed guests along Pennsylvania Avenue, insisting all the while: "I'll take the cold over the heat any day."