Residents across the Greater Toronto Area and Durham Region should prepare for a damp and potentially turbulent day as the Southern Ontario Weather Alert takes effect this Tuesday, May 5, 2025. Environment Canada has issued a forecast predicting significant rainfall and unstable atmospheric conditions that could lead to thunderstorms throughout the morning and afternoon hours. For those living in Oshawa and the surrounding Durham municipalities, the day will begin with heavy cloud cover and a high probability of precipitation.
According to the latest meteorological data, there is a 40 to 60 percent chance of showers during the morning commute in major urban centers including Toronto, Mississauga, Brampton, and Oshawa. The Southern Ontario Weather Alert emphasizes that while the rain may start as a light drizzle, parts of southern Ontario—particularly the Niagara region and coastal areas—could see cumulative rainfall totals reaching up to 20 mm by the end of the day.
The primary concern for residents today is the risk of thunderstorms during the morning period. These storms may bring localized heavy downpours and reduced visibility on major highways like the 401 and 407. Additionally, wind gusts are expected to intensify, reaching speeds of up to 40 km/h across the GTA. Despite the grey skies and wet conditions, temperatures will remain relatively mild for early May, with a projected daytime high of approximately 15°C.
As the system moves through the region, the shower activity is expected to persist into the afternoon. The Southern Ontario Weather Alert indicates that while the thunderstorm risk may diminish after midday, a steady rain will likely continue. Regions further south, such as Niagara Falls, St. Catharines, and Welland, are anticipated to bear the brunt of the system, with an additional 15 mm of rainfall possible overnight on Tuesday.
Looking toward the middle of the week, the weather is expected to take a cooler turn. Wednesday’s forecast remains mostly cloudy with a lingering 40 percent chance of showers. However, the temperature is set to drop to a high of 11°C, with overnight lows dipping significantly to a chilly 1°C.
Homeowners in Durham Region are encouraged to ensure that gutters and storm drains are clear of debris to handle the sudden influx of water. Drivers should also exercise extra caution, as the combination of first-spring rains and oil residue on the roads can create slick driving conditions. This Southern Ontario Weather Alert serves as a reminder that May weather in Ontario remains highly unpredictable as the province transitions into the warmer summer months.
