Environment Canada has issued a special weather statement for Toronto.
The weather agency says that some incoming thunderstorms could bring heavy downpours, with rainfall of up to 50 mm in some areas.
The showers have already hit Windsor and Sarnia. Environment Canada says they will reach parts of the GTA as early as 4 p.m. This may cause problems for drivers, who are advised to monitor any upcoming forecasts in case a warning or watch is issued.