Environment Canada is warning of a heavy snowfall on Wednesday for London, Komoka, Parkhill and Strathroy, along with western and eastern Middlesex County.
The weather agency says lake effect snow squalls are forecasted to develop in Goderich and Wingham on Wednesday morning and then later extend into the London area during the afternoon.
If the heavy snow hits, reduced visibility can be expected, along with winds blowing at 30 kilometres per hour and gusting up to 60 kilometres per hour.
Environment Canada says up to 20 centimetres of snow may be possible in certain areas.
Drivers are advised to used caution due to hazardous road conditions and sudden changes in the weather.
The snow squalls are expected to taper off overnight on Wednesday.