It may be time to think about assembling lumber to build an ark.
Environment Canada warns some parts of the province could see close to a month's worth of rain in the span of just a few days starting Thursday. The agency has issued a special weather statement covering much of Southern and Eastern Ontario
Forecasters expect to see rainfall amounts between 40 and 70 mm by the time rain tapers off this weekend. Toronto typically sees 74mm of rain in the entire month of May.
With the ground already saturated from heavy rains in April, officials worry about potential flooding as more rain comes down.
Toronto was soaked by 108 mm of rain in April. 63 mm is about average.
There have already been problems with flooding this week with Lake Ontario waters spilling over shorelines. Residents of some beach-front properties in Bowmanville were shin-deep in water this week.
New York Governor Andrew Cuomo has declared a state of emergency in flooded areas along Lake Ontario's southern shore. He has also demanded that an international commission release water through a dam to lower the lake level.
With files from the Associated Press and Hayley Cooper