After a balmy start, winter gave Londoners the cold shoulder yesterday. Western Canada's cold front has drifted eastward, cutting short Southwestern Ontario's love-in with unseasonably high temperatures.

The deep freeze will plunge the region into temperatures forecast as low as -16C this week, with daytime highs through Sunday not expected to eclipse the zero mark.

Today's low temperature is expected to fall a few degrees shy of the -15 needed to trigger a cold-weather alert, but the Middlesex-London Health Unit advised people to take precautions.

"A lot of it is common sense," said public health nurse Mag Yost, advising everybody to wear warm clothes to avoid frostbite and hypothermia.

While keeping warm seems like common sense for most, the cold weather presents challenges for the city's homeless, who have flocked to shelters, said Capt. Neil Lewis, spokesperson for the Salvation Army in London.

The Salvation Army's "soup van" served a warm meal to 57 street people Monday night and offered them blankets and clothes, Lewis said.

Although icy roads and snow weren't a major problem in most of the region yesterday, OPP reported one serious accident -- amid blowing snow -- in Elgin County.

Paramedics took a 25-year-old London woman to hospital with serious injuries after her car collided with an SUV on Highway 4, just south of the Ford St. Thomas assembly plant.

Police say the SUV's 58-year-old driver suffered minor injuries.

Low temperatures also kept tow trucks busy across the region.

"We've had double the amount of calls we'd normally have," said John Matthews, spokesperson for the Canadian Automobile Association in Western Ontario.

Most of the calls were for boosts and tows, Matthews said.

Some students in the Avon Maitland school district had the day off yesterday after heavy snow caused several schools to close.

But the cold snap has also given skiers a late Christmas present.

"It couldn't have come any sooner," said Tim Oliver, marketing director of the London Ski Club at Boler Mountain, which has seen business double over the past two days.

Recent spring-like temperatures had kept skiers away from the hill.