Environment Canada has issued a rainfall warning for much of southern Ontario with up to 50 mm possible in some areas.
The warning says flooding is possible today in some low-lying areas.
The warning includes the Greater Toronto Area and extends from Belleville in the east down to Windsor and up to the Bruce Peninsula and Barrie.
The Toronto forecast for Thursday calls for a high of 14 C with the drizzle changing to rain by about noon and thunderstorms in some areas.
As of 6 a.m., the temperature is 2 C.