The Washington area plunged into its deepest freeze of the winter yesterday with low temperatures stalling cars, freezing pipes, crippling furnaces and wreaking havoc in general.

With the temperatures expected to remain far below normal through the weekend, National Weather Service forecasters could give little solace and suggested only that residents hunker down and ride it out.

Low temperatures in the single-digit range -- from 5 to 10 degrees -- were anticipated for both this morning and tomorrow morning. High temperatures were expected to remain below 30 degrees.

By 1 a.m. today the mercury had sunk to 12 degrees at National Airport, and to 8 at Dulles.

Area plumbers, heating engineers and gas station owners offered a number of tips to help overcome or avoid the problems of extreme cold.

Your car: to avoid running the battery down, turn the headlights on for no more than 30 seconds before trying to start the engine. This draws some limited current from the battery but also warms it, making it more efficient.

Turn the lights off and make sure all other battery-dependent accessories are off. Then push the gas pedal slowly all the way to the floor once or twice. Take your foot off the pedal and turn the ignition key. The car should start.

Frozen car door locks: pour boiling hot water into the lock, but make sure the water is boiling to prevent refreezing. An alternative is to direct the heat from a hair dryer at the lock, although that will take longer. Also, a small torch or cigarette lighter can be used, but be careful to avoid burning the car's paint job.

Frozen pipes: to prevent this from happening, shut off water to all exterior pipes or pipes near exterior walls possible. Otherwise, let the faucet run at a trickle so the water does not stand in the pipe. Electrical tape can also be wrapped around the pipes to help retain heat. Open up cabinet doors under sinks that are next to exterior walls to allow a freer flow of room temperature air around the pipes.

If you already have frozen pipes, you can attempt to unfreeze them with a hair dryer or other heat-throwing accessory. If that doesn't work, call a professional welder who can melt the ice with special electrical devices.

Disabled furnace: if you're going to be without central heat for an extended period, close off all unnecessary portions of your home. Cover windows with heavy drapes or other material. Seal edges of windows and doors with tape where possible. Use electric space heaters or gas stoves and ovens, but with caution. Do not leave them on continuously, and if you are using a gas stove and oven in a small sealed area, open a window slightly for ventilation.

The normal high daytime temperature at this time of year is 45 degrees and the normal low at night is about 28 degrees.