A storm expected to create messy travel conditions for the evening commute hit much of southern Ontario on Wednesday, bringing snow to a wide expanse of the province while gradually moving east.

Snowfall warnings were in effect for most of southern and eastern Ontario, with Environment Canada predicting up to 20 centimetres of snow in several regions including the Greater Toronto and Hamilton Area.

Windsor and Niagara were forecast to see up to 15 centimetres of snow while the GTA was expected to get up to 20 centimetres as the storm progressed.

Environment Canada warned the rapidly accumulating snow could lead to possible isolated power outages, reduced visibility and difficult travel.

“People who are motorists should allow a lot of extra time to reach their destination and if they don’t have to drive today, don’t,” Rob Kuhn, a severe weather meteorologist with Environment Canada, said in an interview.

“There’s probably going to be a significant impact on the rush hour commute home this afternoon across much of southern Ontario.”

GO Transit, which serves the Greater Golden Horseshoe, adjusted its schedule due to the storm and advised riders to plan for extra travel time. The Toronto Transit Commission said it had plans in place to ensure service was maintained.

Premier Doug Ford warned Ontarians of “treacherous” driving conditions expected as a result of the storm. “Please avoid driving unless absolutely necessary,” he wrote on Twitter.

Eastern Ontario was expected to see snow later Wednesday and into Thursday. Ottawa, Kingston and most of eastern Ontario are expected to see accumulations of up to 20 centimetres of snow, Environment Canada said.