In Canada, there are two types of severe thunderstorm alerts. Severe thunderstorm watches and severe thunderstorm warnings.

A watch is issued when: conditions are favourable for the development of severe thunderstorms with one wind gusts of 90 km/h or greater, which could cause structural wind damage; hail of two centimetres (cm) or larger in diameter; or heavy rainfall, as per rainfall criteria, excluding those for winter and during thaw.

A warning is issued when: there is evidence-based on radar, satellite pictures, or from a reliable spotter that any one or more of the following three weather conditions is imminent or occurring: wind gusts of 90 km/h or greater, which could cause structural wind damage; hail of two centimetres (cm) or larger in diameter; or heavy rainfall, as per rainfall criteria, excluding those for winter and during thaw.