The Lake Simcoe Region Conservation Authority advises that a line of severe thunderstorms moved across the watershed early this morning, producing between 20 mm and 50 mm of rain in less than an hour. The Lake Simcoe Region Conservation Authority has received localized reports of flooding caused by this morning’s thunderstorms. There is still an additional 20 mm of rainfall in the forecast across the watershed through the remainder of today, with higher local amounts possible where further thunderstorms develop.
Localized flooding in low-lying areas, ponding of water on roads, and rising water levels and flows in rivers and streams are possible and may already be occurring in areas that received the heaviest rainfall. With additional rainfall expected today, water levels and flows may rise rapidly over the next 24 hours, particularly in areas receiving heavier rainfall.
The rainfall will increase flows in local watercourses, causing streams and rivers to become dangerous, particularly in the vicinity of bridges and culverts. Children and pets should be warned to stay away from all watercourses.
This Watershed Conditions Statement – Flood Outlook will be in effect through Thursday, Sept. 3, 2026, at noon, or until otherwise updated or cancelled.
For further information, contact duty officer Mohammad Hajiseyedjavadi.