From heat warnings to frost advisory in southern Ontario

Sunrise in Baden, Ont. on April 18, 2026. (Courtesy: William Wirtz)

Southwestern Ontario is in the middle of another wild weather swing.

Heat warnings were issued Monday as the temperature soared to 29 degrees Celsius, though it felt closer to 36.

The heat continued into Tuesday. Environment Canada said it reached a high of 28 degrees Celsius during the day.

Wednesday, however, was a different story.

Forecasts showed a high of only 14 degrees Celsius and, while it was sunny, wind gusts made it feel cooler.

Anyone heading out early Thursday should bundle up. Environment Canada has issued a frost warning for the morning. They said temperatures could drop to or below the freezing mark, and could impact plants, trees and plants.