Residents of Mississippi Mills, Ontario, should prepare for a period of unseasonably warm weather followed by a significant temperature drop and the possibility of thunderstorms through Tuesday, May 19, 2026.
According to The Weather Network, the community is currently seeing temperatures of 28°C on Tuesday, with a forecast high of 30°C — well above the historical average high of approximately 20°C for late May. The temperature will feel closer to 36°C. Residents should be aware of a 70 percent chance of thunderstorms during the evening, which could bring 1-3 mm of rainfall.
The unsettled weather is being caused by a powerful cold front moving into the region. While the area is currently experiencing summer-like heat, The Weather Network reports that a sharp cooldown is expected by Wednesday morning. Some parts of Ontario — including Barrie and London — may see temperatures plummet by more than 20 degrees in less than 24 hours as the front passes through, though Mississippi Mills is forecast to see a drop to around 17°C on Wednesday.
The potential for severe weather across southern Ontario remains a concern, with forecasts indicating the possibility of large hail, heavy rain, and damaging wind gusts. Mississippi Valley Conservation Authority has downgraded its flood warning; as of mid-May, the watershed is at normal status, though officials continue to monitor water levels for any impact from expected rainfall.
As conditions change, residents are encouraged to monitor Environment Canada for any official weather alerts or warnings that may be issued for the region.
