A special weather statement has been issued for Windsor-Essex.
Environment Canada says 10-20mm of rain is expected overnight along with rapidly falling temperatures which will create very icy conditions and hazardous road conditions.
Local utility outages are possible.
Winds from the west/northwest will also reach 60-80 km/h before easing Friday night.
Showers will change to flurries through Friday as a strong cold front passes through the region leaving about 2 cm of snow.
Flurries and snow squalls off Lake Huron and Georgian Bay are also expected.