Environment Canada has issued a snow squall watch for Watford, Pinery Park, and Eastern Lambton County.
There's a Winter Weather Travel Advisory issued for Western Lambton County, including Sarnia.
The national weather agency says squalls are expected to develop Thursday evening and into Friday.
Under the snow squall bands, visibilities will be significantly reduced due to the heavy, and quickly accumulating snow.
Squalls are likely to develop to the southeast of Lake Huron and Georgian Bay on Thursday evening and are expected to persist well into the day Friday.
Total snowfall accumulations in excess of 15 cm are possible for areas that receive multiple snow squalls.
Temperatures are expected to rapidly decline due to a cold front that will move over Southern Ontario prior to the development of the squalls.
Travel may be hazardous due to sudden changes in the weather. Visibility may be suddenly reduced at times in heavy snow.
Public Safety Canada encourages everyone to make an emergency plan and get an emergency kit with drinking water, food, medicine, a first-aid kit and a flashlight. For information on emergency plans and kits go to http://www.getprepared.gc.ca/
Snow squall watches are issued when conditions are favourable for the formation of bands of snow that could produce intense accumulating snow or near zero visibility.