Southern Ontario: Snowfall Outlook for Saturday, December 18, 2021

Forecast Discussion

A system is expected to slide across the Lower Great Lake on Saturday and bring accumulating snowfall to parts of Southern Ontario. Precipitation will start to move into our region from the west during the mid to late morning hours with snowfall spreading eastward throughout the late morning. Eastern Ontario should see the first flakes sometime around the lunch hour and will further intensify later in the day. This steady snowfall will continue throughout the afternoon and into the early evening before clearing from west to east. We expect the bulk of the snow to be finished by midnight although flurries may continue to linger around into the overnight hours, especially for Eastern Ontario. Closer to Lake Erie and into Deep Southwestern Ontario, it will be just warm enough to allow for some rain to mix in with the snow which would reduce accumulation.

We’re looking at widespread snowfall totals ranging from 6-12cm from Sarnia to London through the GTA and into much of Eastern Ontario. There is the potential for a few areas to approach 15cm, especially over the higher elevations of the Dundalk Highlands and along the Internation border in Eastern Ontario. Lower amounts for regions east Georgian Bay where less moisture will be present along with the Lake Erie shoreline due to the mixed precipitation. Blowing snow could be an issue around Lake Ontario where wind gusts may reach 30-50km/h during the day on Saturday.