Calgary and southern Alberta have experienced a relatively warm winter so far but an arctic air mass moved in overnight and temperatures are expected to tumble into the minus 20s this weekend.

A snowfall warning has been issued for the mountain parks and parts of central and northern Alberta.

Environment Canada says a slow moving system will bring heavy snow to some areas and total accumulation could be between 15 and 40 cm, depending on the region.

People are being advised to postpone unnecessary travel in those areas until conditions improve.

CTV Calgary Meteorologist Kevin Stanfield says Calgary will see some snow over the next few days but that it likely won’t amount to more than 5 cm.

CTV Calgary five-day forecast:

Friday: Mainly cloudy, flurries, early high -8, falling to -15
Saturday: Mainly cloudy, flurries, high -15
Sunday: Mainly cloudy, flurries, high -23
Monday: Flurries, high -24
Tuesday: Sunny, high -16

The cold weather increases the risk of frostbite and hypothermia for people who are exposed to the conditions for more than a few minutes or who work outside.

First responders say people should wear extra layers and limit their time outside to reduce the risks.

The AMA is also advising motorists to plug in their vehicles if they park outside and says that it typically sees a 40 per cent increase in service for dead batteries in the extreme cold.

Roads in and around the city are snow covered and there are some slippery sections on area highways.

City crews are out plowing, salting and sanding priority routes.

Motorists are being advised to drive to conditions.

WEATHER AND ROAD RESOURCES

For updated information regarding weather warnings and watches, visit Environment Canada – Public Weather Alerts.

For the latest on road conditions in Calgary, follow  YYC Transportation on twitter or check the CTV Calgary Traffic Page HERE.

For updates on highway conditions, follow 511 Alberta on twitter, visit AMA Roads Reports and the DriveBC sites.

Download the CTV Calgary Sky Watch Weather App for real-time weather forecasts and video updates on conditions HERE.

For more information on the city’s snow removal process, click HERE.