Happy holidays, Montreal! After 20 centimetres of snow last week, we're officially having a white Christmas — but it's going to be one heck of a windy one, too. At 4:45 a.m. on December 25, Environment Canada issued a blowing snow advisory for the Montreal Island area, Longueuil (Varennes area), Laval and Châteauguay (La Prairie area), which is expected to cause poor visibility in snow and blowing snow in some locations.