The March 21 weather Southern Ontario forecast is expected to bring a mix of fog, clouds, and rain as the weekend begins, continuing the trend of unsettled early spring conditions across the region. While temperatures remain relatively mild compared to earlier in the week, changing conditions may impact visibility and travel across parts of southern Ontario, including Durham Region.
According to Environment Canada, Saturday morning will start off cloudy with fog patches developing across major areas such as Toronto, Mississauga, Brampton, Hamilton, Oshawa, and Niagara Falls. The fog may reduce visibility for drivers during early hours, especially in low-lying areas and near bodies of water. Residents are advised to exercise caution during morning commutes.
Daytime temperatures are expected to reach around 6°C, which is typical for early spring. Despite the cloud cover, the UV index is forecast to range between 3 and 4, considered moderate, meaning some sun exposure protection may still be necessary when outdoors.
As the day progresses, conditions will remain mostly cloudy, with rain expected to move in later. Saturday night is forecast to bring a 60 per cent chance of showers, particularly across the Greater Toronto Area. Winds could also pick up, with gusts reaching up to 40 km/h, adding to the unsettled weather conditions.
Overnight temperatures will drop to around 2°C in areas like Mississauga, while slightly warmer conditions are expected in places such as Hamilton, where temperatures may rise to around 7°C by Sunday morning. These fluctuations highlight the typical variability of early spring weather in southern Ontario.
Sunday is expected to continue the wet pattern, with periods of rain throughout the day and a daytime high near 7°C. By evening, conditions will remain cloudy with a 30 per cent chance of showers or flurries, and temperatures are forecast to dip to around -1°C overnight, bringing a slight risk of icy conditions in some areas.
Looking ahead to Monday, the forecast includes a 30 per cent chance of flurries, with temperatures hovering around 3°C. This mix of rain, snow, and fluctuating temperatures reflects the transitional nature of the season, where winter conditions can still briefly return even after the official start of spring.
The March 21 weather Southern Ontario forecast serves as a reminder that early spring often brings unpredictable conditions. Fog, rain, and occasional flurries can all occur within a short period, requiring residents to stay prepared and monitor weather updates closely.
Drivers are encouraged to remain cautious, particularly during foggy mornings and rainy evenings, while pedestrians should be mindful of slippery surfaces as temperatures fluctuate. Dressing in layers and planning for both wet and cool conditions will help residents stay comfortable throughout the weekend.
As southern Ontario continues its transition into spring, this weekend’s weather highlights the gradual shift from winter to warmer days ahead.
