Washington suffered through its coldest day in nearly 50 years yesterday as water pipes burst, furnaces quit, cars died and anyone who could remained indoors. Transit officials, bracing for a chaotic morning rush-hour, said the extreme cold and Metro equipment problems would make things even worse.

Yesterday's low temperature of 5 degrees below zero, recorded at 7 a.m. at National Airport, was the coldest reported in Washington since Feb. 9, 1934, when it was minus 6. The reading also was the airport's first subzero reading since the National Weather Service opened operations there in 1942. The lowest temperature ever recorded in Washington was minus 15 on Feb. 11, 1899.

Northwest winds made it feel even colder, creating a wind-chill effect as low as 44 degrees below zero, the weather service said.

Occasional light snow and more numbing cold -- with temperatures falling as low as 10 below zero -- were predicted for overnight as a cold Canadian air mass lingered over the region, the weather service said. Temperatures were expected to climb into the 20s later today.

The extreme cold further complicated the city's efforts to end the disruptions brought on Wednesday when a jetliner crashed into the 14th Street bridge and a Metro train derailed underground within 30 minutes of each other. Yesterday divers made little progress in recovering more bodies or wreckage from from the Air Florida 737 that hit the bridge and sank into the Potomac after taking off from National Airport.

The center span of the 14th Street bridge remains closed today, but Metro yesterday reopened the entire Orange/Blue rail line for the first time since the fatal crash last week at Federal Center SW. Despite the reopening, Metro officials nonetheless predicted more headaches for commuters because of new maintenance trouble on Metrorail, and because cold weather is expected to sideline a number of Metro buses.

"Rush hour is going to be lousy and whammed-up," Metro spokesman Cody Pfanstiehl said. "We still have the weather whammy and the 14th Street bridge whammy and now this rail whammy . . . We are triple-whammied."

Metro has 20 to 25 inoperable rail cars because its maintenance crews have been tied up repairing tracks and clearing debris and could not work on the cars, which in some cases have cold-related malfunctions, he said. Many cars were cut off from their maintenance yards during the four days that the rail tunnel was closed from Federal Center to McPherson Square..

Metro will operate its customary 43 trains on the three lines today, but many will be four-car instead of six-car trains. The sidelined cars represent nearly 10 percent of Metro's total of 262 cars used for weekday rush-hours, according to Pfanstiehl. The Blue line to National Airport will be assigned as many cars as possible to compensate for heavier crowds expected because of the bridge shutdown, he said.

Metro also is expecting substantial delays on many Virginia bus routes because of the bridge closing. Delays could be worsened, Pfanstiehl said, depending on how many buses won't start or operate properly in the intense cold. "Every major city has this problem in cold weather," he said.

Transportation officials were predicting monumental tie-ups despite Metro's fully functioning rail and bus service today. The closing of the 14th Street bridge's center-span express lanes has forced the rerouting of thousands of commuters expected to clog the other bridges across the Potomac River.

The intense cold apparently froze water pipes in at least 400 District homes, according to the D.C. Bureau of Water and Sewer Services, which was also contending with at least eight major underground water-main breaks. Of the 400 homes, about 200 reported ruptured water pipes with flooding in some cases, officials said.

"This is the worst we've ever had," said Marinoff Collins, a general foreman who has worked with the water department for 20 years and who yesterday was scrambling to call in additional workers to supplement the 25 working on broken pipes around the city.

A separate work crew struggled to repair the broken cast-iron water mains that flooded -- and then glazed over -- several major intersections, including New York Avenue and 1st Street NE, and Massachusetts Avenue and 3rd Street NW. At those sites, streets were closed and heavy equipment was used to scrape off ice up to eight inches thick, according to the D.C. Transportation Department, which expected to have the intersections cleaned up for today's traffic.

Suburban jurisdictions had similar problems, with hundreds of homes and businesses suffering ruptured pipes. Broken water pipes flooded and closed restaurants, shops and the movie theater on the lower level of Tysons Corner shopping mall.

About 100 Washington buildings, including several large apartment houses, yesterday lost heat because furnaces malfunctioned or exhausted their oil supply, according to Mayor Marion Barry's emergency command post. Sam Jordan, acting deputy director of the command post, said that if landlords couldn't be located, the city in some cases was making emergency oil deliveries and billing landlords. Liens will be made on the properties if landlords do not pay, he said.

The city's shelters for the poor and homeless were operating at or beyond capacity yesterday, and some were staying open all day rather than just overnight. The city-run Blair shelter at 611 I St. NE and Pierce shelter at 14th and G Streets NE, were each beyond their 140-bed capacities yesterday, said Lamont Dozier, a staff member. "When the beds run out, they just sit up in the TV room and we try to make them as comfortable as possible . . . we don't put anybody out."