Joined: Jan 2009
Posts: 44,178
Likes: 6,412
From: New York, NY, and High Falls, NY, USA
Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem
Did you know that -40ºC equals -40ºF? It's true!
There is a winter cycling section of bikeforums. Take a look. There are a few Canadians and Minnesotans and the like who commute in pretty much all kinds of winter weather.
This seems like a good idea. Even in the worst weather, you should be safe if 4km is the greatest distance you have to cover. In fact, it may be safer than in a car.