Environment Canada has issued a rainfall warning for Toronto and Durham Region as up to 60 mm of rain is possible by the end of Thursday.
The weather agency said, at around noon, about 35 mm of rain has already fall in the area.
But another 20 mm of rain is still expected for areas east of the Don Valley Parkway before the rain tapers to showers in the evening.
“Heavy downpours can cause flash floods and water pooling on roads,” Environment Canada said. “Watch for possible washouts near rivers, creeks and culverts.”
Thursday’s rain comes amid a stretch of rainfall that began on Wednesday and is expected to last until late Friday.
Toronto has been experiencing a stretch of unusually low temperatures that haven’t been seen in late May in decades — as far back as a previous record low set on May 22, 1967.
Meteorologist Geoff Coulson, from Environment Canada, said the daytime high for Thursday, which is around 10 C to 11 C, is the normal nighttime low temperature for this time of year, and significantly below the typical daytime high of 20 C.
“In fact, the record for the coldest daytime high temperature at the airport in Toronto for May 22 … is 9.4 degrees, set back in 1967,” he said.
Coulson said a cold front swept through southern Ontario on Sunday, bringing the cooler temperatures this week.
NEW: Rainfall warning issued for Toronto and southern Durham Region. Rain totals are already over 40mm in some areas with an additional 20mm possible before rain tapers to showers this evening. pic.twitter.com/Kas0bg9khq
— Anthony Farnell (@AnthonyFarnell) May 22, 2025