Trick-or-treaters in Huntsville and Parry Sound will have to dress warm on Friday. This year, Hallowe’en will mark the first official snowfall of the season. Environment Canada says a low pressure system developing over Eastern Lake Superior today will track southeast towards the Lower Great Lakes. An area of precipitation will continue until Friday night bringing possibly 5 to 10 cm of snow. Flurries will then taper off early Saturday as the low system pulls away to the southeast.