It would be wise to postpone any park picnics you've got planned over the next 24 hours in Toronto, where up to 50 mm of rain is expected to drench the city in short order.

Environment Canada issued a special weather statement for the city at 1:26 p.m. on Monday afternoon, warning of "significant rainfall" amounts coming down between now and Tuesday night.

"Showers and occasional thunderstorms are expected to move across the region as a cold front approaches from the west," wrote the federal weather agency in its statement. "The precipitation is expected to end by Tuesday evening in the wake of the cold front."

So, it's going to get wet and cold, basically. Even colder than it already is. 

Temperatures will be lower than what we've experienced in Toronto so far this summer between now and Friday, if meteorologists are correct. Image via Environment Canada.

"There is some uncertainty with the track and timing of this cold front that will move across the area. Hence exact timing and total rainfall amounts are subject to change," notes Environment Canada.

Total rainfall amounts of 25 to 50 mm are expected across much of Southern Ontario, though "locally higher amounts are also possible in areas that receive thunderstorms."

Temperatures are expected to bottom out around 12 C on Tuesday evening when the aforementioned cold front hits. Wednesday and Thursday should reach the low 20s, though both also have precipitation risks in the forecast.

Rainfall warnings are currently in place for several parts of Southern Ontario and could be expanded to Toronto based on how the storm tracks and how strong it is.

"Heavy downpours can cause flash floods and water pooling on roads. Localized flooding in low-lying areas is possible," warns EnviroCan for regions with rainfall warnings. "Please continue to monitor alerts and forecasts."