The Barrie News reports that a frost advisory is now in effect for parts of southern Ontario, just one day after the region experienced a heat warning. The sudden shift in weather has caught many residents off guard, as temperatures are expected to dip near freezing overnight.
Weather Whiplash Strikes Ontario
According to the report by Jocelyn Martin, published on May 20, 2026, at 6:15 PM EDT, the frost advisory comes as a stark contrast to the previous day's heat warning. The advisory warns that frost could damage sensitive plants and crops if left unprotected. Residents are advised to cover or bring indoors any vulnerable vegetation.
The rapid temperature swing is attributed to a cold front moving through the region, bringing cooler air behind it. While heat warnings are typically issued when temperatures pose a risk of heat-related illness, frost advisories are issued when temperatures are expected to drop to near or below freezing during the growing season.
Impact on Local Agriculture
Local farmers are particularly concerned about the potential for frost damage to early-season crops. The advisory covers a wide area including parts of the Greater Toronto Area, though the exact boundaries may shift as the front moves. Officials recommend monitoring local forecasts closely.
This weather event follows a series of other news stories from the region, including a police operation in Regina, a fire on a remote island near Sudbury, and a fatal crash involving a Walkerton teacher. However, the frost advisory is the primary focus for many residents as they prepare for the cold night ahead.
Safety Precautions
To protect plants, gardeners are advised to use cloth covers or bring potted plants indoors. The frost advisory is expected to remain in effect through the early morning hours of May 21. After that, temperatures are forecast to moderate, returning to seasonal norms.
