Thunderstorms can bring lightning, heavy rain, hail, strong winds and tornadoes. Each year on average in Canada, there are between two and three lightning-related deaths and 180 lightning-related injuries1.
Environment Canada issues warnings when severe thunderstorms are imminent or already detected, which are distributed through emergency warning systems such as Alert Ready (found on TV, radio, and smartphone channels), and weather applications.
Severe Thunderstorm Watch: A severe thunderstorm watch is issued when conditions are favourable for the development of severe thunderstorms with one or more of the following conditions:
- 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
Severe Thunderstorm Warning: A severe thunderstorm 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