Ontario trick-or-treaters can expect bitter-cold temperatures to close out October, and that's not even close to the worst of the forecast in store for the peak of spooky season and the days to follow.

Plummeting temperatures have been the big weather story in the province in recent days, and some Ontario residents kicked off the week with their first taste of snowfall for the season on Monday.

Deposits of up to 2 centimetres in Ottawa and lighter snowfall in areas near Georgian Bay and Lake Simcoe were just an appetizer for the main course that may arrive in this area of the province on Tuesday night.

Cold temperatures in typical snowbelt regions have set the stage for wet lake-effect snow in what could be the first major snowfall event of the season.

According to The Weather Network, scattered snow squalls on Tuesday evening have the potential to "accumulate over 10 cm near the snow belts, cottage country and between Sarnia to London," while a graphic produced by the service shows the potential for 10-15 centimetres in areas near Parry Sound.

October will end on a frigid note across southern Ontario as much colder temperatures settle in and the chance for snow sets up in time for trick-or-treating. #ONwx https://t.co/jxyAmzNmrn

— The Weather Network (@weathernetwork) October 31, 2023

Turbulent conditions should ease by Wednesday, though snow showers could still be on tap for areas of Southwestern Ontario spanning from London to Sarnia.

Aside from some shivers, Toronto and the broader GTA region are expected to be spared from this winter preview, and the city will even see a reprieve from colder temperatures when the mercury is forecast to swing back up to daytime highs in the double-digits in time for the weekend.