ONTARIO — A significant January thaw is moving across Ontario, bringing unseasonably warm temperatures, rain and the potential for record-breaking highs in several regions, according to Environment Canada.
The warmup began Wednesday, January 7, and is expected to peak on Friday, driven by a low-pressure system pushing warm air northward into the province. Meteorologists say the system could challenge daily temperature records in parts of southern and northern Ontario.
The warmest conditions are forecast for extreme southwestern Ontario, where communities southwest of London — including Windsor, Leamington, Essex and Sarnia — could see daytime highs reaching 14°C to 15°C on Friday.
The Greater Toronto Area, including Toronto, Peel, Halton, York, Durham and Hamilton, is expected to experience temperatures near 10°C, while regions east toward Ottawa and areas north such as Barrie, Orillia and Gravenhurst are forecast to see high single-digit temperatures. The Ottawa Valley may reach 7°C to 8°C.
Northern Ontario is also expected to feel the impact, with some communities north of Sudbury and toward Timmins potentially breaking daily high temperature records earlier in the week.
Rain, Flood Watches and Mixed Winter Weather
With above-freezing temperatures and rain in the forecast, several conservation authorities have issued flood watches, particularly in low-lying and flood-prone areas. Southern Ontario could receive 5 to 15 millimetres of rain, while regions east of Georgian Bay may see 15 to 30 millimetres.
As the system progresses, weather conditions will vary across the province. Central Ontario could receive 10 to 20 centimetres of snow over the weekend, while parts of southern and eastern Ontario may experience freezing rain, creating potentially hazardous travel conditions. Northeastern Ontario, including Timmins, may see 5 to 15 millimetres of snowfall.
Short-Lived Warmth
Meteorologists caution that the thaw will be short-lived, with temperatures expected to return to more seasonal January norms early next week as colder air moves back into the province.
Residents are advised to monitor local weather forecasts, remain alert to flood warnings, and take precautions as rapidly changing winter conditions continue across Ontario.