Environment Canada is the official source for weather information, forecasts and alerts in Canada. When Environment Canada determines that damaging, heavy rain is likely or is occurring, a Heavy RainfallWarning will be issued. In these situations, expect 50 mm of rain over 12 hours or less, or 80 mm of rain in less than 24 hours.
The Ontario Ministry of Natural Resources and local Conservation Authorities are responsible for forecasting when and where flooding is likely to occur, and for issuing three types of flood messages:
Watershed Conditions Statement – Flood Outlook/Water Safety – is issued when general watershed conditions are being assessed for high runoff potential that could lead to flooding, and to remind the public of general river safety issues.
Flood Watch – notifies the public that flooding is possible within specific watercourses and municipalities.
Flood Warning – this is the most serious message. It means that flooding is imminent or occurring within specific watercourses and municipalities. Municipalities and residents should take action to deal with flood conditions, which could include road closures and evacuations.
Visit the website of the Office of the Fire Marshal to read information about flood safety, and view this Flood Pamphlet to learn how to prepare for flooding.