A blast of cold air from Canada is expected to send temperatures plummeting across the United States this weekend, as an unseasonably warm winter will finally get a dose of subzero conditions over Valentine's Day weekend.

The polar vortex is predicted to shift southward, sending cold, Arctic air that has largely been trapped in Canada during the winter plunging into the Midwest and Northeast and chilling the region for at least a few days, the Weather Channel says. The bitter cold could burst pipes, kill car batteries and cause power outages. People planning to be outside for extended periods of time, and their pets would be at an increased risk of hypothermia and frostbite.

Here's what to expect, from the Weather Channel: Friday night: Great Lakes states and upstate New York will get lows approaching or below zero, while the Northeast will feel low 20s and high teens temperatures, as the cold snap moves in from Eastern Canada.

Great Lakes states and upstate New York will get lows approaching or below zero, while the Northeast will feel low 20s and high teens temperatures, as the cold snap moves in from Eastern Canada. Saturday: Highs will crack the teens in Chicago and Detroit, with the rest of the Great Lakes staying in the single digits. Boston will start to chill with 17-degree highs, while New York and Washington, D.C. will hit the mid-20s.

Highs will crack the teens in Chicago and Detroit, with the rest of the Great Lakes staying in the single digits. Boston will start to chill with 17-degree highs, while New York and Washington, D.C. will hit the mid-20s. Saturday night: The piercing cold makes its fury felt. The upper Midwest will stay in the single digits, while Boston will get lows of minus 3 degrees. Windchill in some parts of Massachusetts could reach minus 34. New York will drop to 4 degrees and Washington 10.

The piercing cold makes its fury felt. The upper Midwest will stay in the single digits, while Boston will get lows of minus 3 degrees. Windchill in some parts of Massachusetts could reach minus 34. New York will drop to 4 degrees and Washington 10. Sunday: Temperatures will resume their regularly scheduled winter programming, with highs going back up into the 20s, 30s and 40s into next week. The temperatures would be a stark departure from the warm winter so far.

Most of the country has experienced record or near-record highs for much of January, as a powerful El Nino has made its presence known. Even during a January snowstorm that dumped more than two feet of snow on some places, temperatures largely hovered around the 20s and low 30 and never made for the bone-chilling blizzard conditions of 2015's storm. How to prevent frozen pipes

Frozen pipes can ruin a home, causing thousands of dollars in damage and temporarily cutting off water supply.

But you can take some steps to keep the water flowing:

Allow a slow drip from hot and cold faucets.

Open cabinet doors to allow heat to get to pipes.

Set your thermostat no lower than 55 degrees. Keep the car battery alive in the freezing cold Car batteries lose more than 35 percent of their strength in freezing temperatures, while engines take twice as much power to start up. It's a recipe for a dead battery, which could leave you stuck in a parking lot or on the side of the highway.