Snowstorm, extreme cold prompt weather alerts across northern Ont.

Frigid temperatures return to the northeast Mild temperatures are expected to drop in northeastern Ontario Monday night. Here is what to expect this week in the 7-day forecast.

The relentless blast of winter continues in northern Ontario with temperatures reaching -45 C with the wind chill again in some areas and another storm will bring up to 20 centimetres of snow.

Environment Canada has issued weather alerts for most of northern Ontario.

EXTREME COLD WARNING

The deep freeze continues and is expected to last several days until Thursday morning, Environment Canada said.

Minimum temperatures of -30 C and -33C will be dropped to - 40 C and even - 45 C with the wind chill in some areas Tuesday evening.

These are the communities included in the extreme cold warning:

"Risks are greater for young children, older adults, people with chronic illnesses, people working or exercising outdoors, and those without proper shelter," Environment Canada said.

"Cover up. Frostbite can develop within minutes on exposed skin, especially with wind chill."

WINTER TRAVEL ADVISORIES

Environment Canada said a low-pressure system will bring snow and blowing snow to the region Tuesday evening.

The snow will be heavy at times and accumulation between 10 – 15 centimetres is expected before it eases Wednesday afternoon.

Travellers should expect hazardous driving conditions and adjust plans accordingly, Environment Canada said in a weather alert Tuesday morning.

"If visibility is reduced while driving, turn on your lights and maintain a safe following distance. If you must drive, be prepared for areas of poor visibility," the national weather service said.

"Surfaces such as highways, roads, walkways and parking lots may become difficult to navigate due to accumulating snow."

The winter travel advisory affects communities from the eastern shores of Lake Superior to the Quebec border and west of Thunder Bay to the Manitoba border.

SNOWFALL WARNINGS

Snowfall amounts up to 20 centimetres are expected in the Thunder Bay area, including surrounding communities in the north and west of Lake Superior.

"A low-pressure system tracking south of the region will bring significant snowfall beginning late (Tuesday) morning. Local blowing snow is also likely. Snow will ease to light flurries by early Wednesday morning," Environment Canada said in its snowfall warning.

Heavy and blowing snow could cause visibility issues for motorists.