Weather warning in effect in Toronto and southern Ontario

Frost risk returns to southern Ontario with potential damage to plants and crops.

A cold snap is settling over southern Ontario, bringing the risk of patchy frost that could impact plants, trees, and early-season crops.

Temperatures are expected to dip near or below freezing early this morning across parts of the region.

The frost threat stretches across Toronto, Mississauga, Brampton, Halton Region, Durham Region, and much of the Golden Horseshoe, particularly in areas that are more prone to colder overnight conditions, according to the warning from Environment and Climate Change Canada.

Map: Environment Canada

Clear skies and light winds are creating the perfect setup for frost to form, allowing heat to escape quickly and temperatures to drop sharply overnight.

The risk doesn’t end with the morning chill. Similar conditions are expected again tonight, increasing the likelihood of another round of patchy frost for areas that remain clear.

Even if frost appears isolated, it can still cause damage. Sensitive plants, budding trees, and crops that have already started growing are especially vulnerable this time of year.

Residents are encouraged to take precautions by covering plants or bringing them indoors where possible — particularly in low-lying or rural areas where colder air tends to settle.

With spring weather continuing to fluctuate, these overnight temperature swings remain a concern for gardeners and farmers across southern Ontario.