Snow squalls were in the forecast for part of Lambton, London-Middlesex, and South Huron counties.
On Saturday around 5:30 p.m., Environment Canada upgraded a snow squall watch for the areas to a warning.
As of Sunday morning, the snow squall warning was still in effect and was expected to last through the afternoon.
The weather agency said 10 to 15 centimetres of snow could accumulate within several hours.
"Colder air continues to move into the area with lake effect snow developing this morning," read the notice. "Northwest winds gusting up to 70 kilometres per hour will also lead to reduced visibility in blowing snow at times."
Conditions are expected to improve by Sunday evening.
Other parts of the province, including Grey, South Bruce, Perth, North Huron, and Elgin are under a Winter Weather Travel Advisory.
The areas are only expected to see 5 cm of snow, but strong winds up to 60 km/h and blowing snow could reduce visibility drastically.
Motorists were advised to postpone non-essential travel. Driving may become hazardous at times because of reduced visibility and changing road conditions.
