The calendar may say late May, but weather officials say there's a real risk of frost overnight for much of southern Ontario including the GTA.
"Widespread frost is expected," Environment Canada said in a severe weather warning issued Friday afternoon.
Ground temperatures are expected to be at — or even below — freezing overnight and into early Saturday, the weather agency said.
Only a few areas may be spared.
"The exception is for areas very close to the Great Lakes where temperatures will remain a couple of degrees above freezing," Environment Canada said.
Fruit crops, vegetables, plants and trees could all be at risk, and the agency urges people to take preventative measures.