Coldest weather of the winter forecast for Montreal

Expect ice fog and mist to form off the St. Lawrence River Friday though Sunday mornings, as the coldest temperatures of the winter thus far move into Montreal. Low temperatures this weekend will be near -20C for Montreal and into the middle -20s in many parts of Quebec and Ontario.

The coldest temperatures so far this winter are anticipated tonight through Sunday morning across southern Quebec, Ontario and New England. Montreal along with parts of eastern Ontario received a surprise 5 to 10cm of snow Tuesday evening in a little less than 6 hours. The snow was part of a weakening low pressure system that was expected to remain well south of the region. Instead the snow moved along the St. Lawrence Valley, with the heaviest falling in the southern suburbs of Montreal as well as off-island locations towards Ontario and New York. Other parts of Montreal including Laval, received less than 5cm. I measured a good 10cm on Ile Perrot.

After a rather mild high of -1.7C (29F) on Wednesday, temperatures have been dropping all day Thursday in Montreal. The high Thursday was -5.4C (22F) reached shortly after midnight. As I write this entry, the mercury is down to -9C (16F). In addition to the colder temperature, winds have been increasing all day and are gusting between 20-40km/h, producing windchill values in the minus teens. Those windchills will continue to drop into the minus 20's through Friday. Overnight lows tonight will be near -18C (0F) and struggle to reach -10C (14F) on Friday. Both Friday and Saturday night will likely be the coldest this winter, down to -20C (-4F) in the city, much colder in the suburbs.

The good news is that winds will ease heading into the weekend. As the arctic air pours into the region tonight, there is a good chance for flurries, with perhaps a centimetre or two locally. Expect cloud cover to persist through Friday, along with blustery, cold conditions and isolated flurries. The sun is expected to return by Saturday.

Temperatures will moderate early next week, with perhaps some flurries by Tuesday as a winter storm moves along the Atlantic coast. As this time the bulk of the snow should remain south of Montreal, but the system will need to be watched.