A snowsquall watch for northeast Lambton County and London-Middlesex continues.
Environment Canada says lake effect flurries will continue Wednesday and are expected to become more organized this evening.
Under the snow squall bands, visibilities may be significantly reduced due to the heavy snow and local blowing snow. Snowfall amounts of 10 to 15 cm per 12 hours will be possible.
Environment Canada Meteorologist Etienne Gregoire says this is our first real stretch of cold weather.
"The lakes are wide open, there's hardly any ice and for the first time, really, so far this winter season, we're really going to get an extended stretch of cold weather and cold air over the lake."
Gregoire expects areas along the lake shoreline, around Goderich through to east of Sarnia, will be hit the hardest.
Motorists are advised travel may be hazardous due to sudden changes in the weather.
- With files from Jake Jeffrey.