An Extreme Cold Warning remains in effect across the London region, with no relief expected until milder air moves in on Friday, while areas to the north are dealing with more snow.

Environment Canada says a prolonged period of severely cold wind chills is expected that could see temperatures hit -35C Wednesday, and -40C overnight into Thursday.

The extreme cold is the result of arctic air combined with strong westerly winds.

With temperatures this low, frostbite can develop in minutes, and those at greatest risk are young children, older adults, those with chronic illnesses, people working or exercising outdoors and anyone without proper shelter.

People are also reminded that if it's too cold to be outside, it's also too cold for pets to stay outside.

Conditions should improve Friday as milder air moves into the region.

A snow squall warning is also in effect for Grey-Bruce, which is also under a blowing snow advisory along with Huron-Perth and Waterloo-Wellington.

Dangerous snow squall conditions are expected to continue through Thursday along Lake Huron with gusting winds causing blowing snow and bringing the possibility of whiteout conditions.

Significant accumulation is possible, but the zero visibility and dangerous wind chill values are the biggest concern.

Blowing snow closes schools and roads

It’s a three-snow-day week and counting for children in midwestern Ontario, where the blowing snow and snows qualls closed schools and some highways in Huron, Bruce and Grey counties again Wednesday.

With upwards of 30 centimetres of snow so far this week, high winds were all that was required to making driving a headache.

There were numerous road closures through the day, and around 5:30 p.m. OPP closed all roads on the Bruce Peninsula and even pulled plows off the road until conditions improved.

Additional closures and updates are available online or by calling Bruce County Roads at 1-866-266-7569.

Early Wednesday afternoon, there were also reports of a multi-vehicle collision closing Highway 9 from Walkerton to Kincardine.

At least seven vehicles were believed to be involved in the collision that left a tractor trailer turned sideways and saw cars sliding into the ditch and each other trying to avoid it.