Residents across parts of southern Ontario are being warned to protect outdoor plants and prepare for chilly overnight temperatures as a frost advisory remains in effect through Friday morning.
According to Environment and Climate Change Canada, patchy frost is expected overnight as temperatures in several regions drop near or below the freezing mark.
The advisory includes areas around London and stretches across the Greater Toronto Area, including Brampton, Mississauga, Milton, Halton Hills, portions of York Region, Durham Region and areas extending toward eastern Ontario and the Ottawa Valley.
Meteorologist Monica Vaswani said daytime temperatures are expected to rise enough on Friday for the frost advisory to be lifted in most areas.
“Places currently in the frost advisory are potentially going to see frost tonight through to Friday morning,” Vaswani said, noting that increased cloud cover could help keep temperatures slightly warmer and reduce frost formation in some locations.
However, areas north of the GTA could continue experiencing colder temperatures into Friday night.
Environment Canada noted that regions including Goderich, York Region and Durham Region remain within the active frost alert zone, while additional areas such as Simcoe County, Peterborough, Kawartha Lakes and North Bay may continue seeing frost conditions into mid-May.
Weather officials are advising residents not to move sensitive spring or summer plants outdoors just yet, as overnight frost can damage vegetation and newly planted gardens.
The weather agency also encouraged residents to stay updated through the official Environment Canada weather website or the WeatherCAN app.
Environment Canada’s weather warning system now uses colour-coded alerts to help residents better understand weather risks:
- Grey alerts indicate special weather statements.
- Yellow alerts warn of possible property damage or health impacts.
- Orange alerts signal significant risks and potential damage.
- Red alerts indicate dangerous or life-threatening weather conditions.
Forecasters say Ontario’s cool spring conditions are linked in part to the lingering effects of the La Niña weather system, which has brought colder temperatures and more active storm patterns across the province this season.
Despite the chilly start to May, meteorologists expect temperatures to gradually warm later this month as weather patterns begin transitioning toward El Niño conditions.