Severe Weather

Thunderstorms, lightning, heavy rain and hail can develop quickly and threaten life and property. Severe storms occur frequently across Alberta and can be unpredictable.

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Before a Thunderstorm, Lightning, Heavy Rain or Hail Event


All thunderstorms are potentially deadly electrical storms, whether or not there is a severe weather warning in effect. Severe weather can bring damaging conditions such as strong winds, hail, lightning, heavy rain and tornadoes.

A series of thunderstorms can last for several hours. Severe thunderstorms or heavy winds cause the most damage in Alberta, not tornadoes. Thunderstorms can bring hazards such as heavy rain, lightning and hail.

During a thunderstorm

  • During a thunderstorm, move to a safe place that is away from windows and doors. Avoid using electrical equipment and telephones.


Each year lightning kills approximately 10 Canadians and injures many more. On average, lightning causes more fatalities in Canada than hail, rain, flooding, wind, tornadoes and hurricanes combined.

If you can see lightning or hear thunder, consider it a threat.

During lightning

  • Seek shelter in a fully enclosed building with wiring and plumbing.
  • Unplug electrical appliances and stay away from outlets.
  • Avoid windows, doors, fireplaces, sinks, tubs and showers because these areas are more likely to pass electricity.
  • Wait 30 minutes after you hear the last rumble of thunder before going outside.

If you are stranded outdoors:

  • Avoid standing near tall objects or anything made of metal.
  • Avoid water and take shelter in a low-lying area, such as a ditch.
  • If you are out on a lake or other body of water, make way for shore immediately and then follow the instructions above.
  • If possible, avoid sheltering in your vehicle. It does not offer significant protection from lightning.

Heavy Rain

Heavy rainfall can cause floods in a short period of time, especially when the ground is frozen or already wet. A heavy downpour warning is issued when 50 millimetres or more of rain is expected within one hour.

During heavy rain

If outdoors during heavy rainfall:

  • Avoid roadway underpasses, drainage ditches, low lying and water collection areas. These areas can flood and overflow very quickly.
  • Stay away from power lines and electrical wires.


Hail forms in storm clouds and is most common in summer, but can also occur during colder times of the year. Hailstones range in size, from small peas to grapefruits, with large hail occurring more in the warmer season.

Hailstones can fall at speeds of up to 100 kilometres per hour or more, and can cause significant damage to homes, property, cars and crops. When combined with heavy rains, hail can clog storm drains leading to flooding.

During hail

  • Immediately take cover when hail begins to fall.
  • Keep yourself and your loved ones, including pets, away from windows, glass doors and skylights.
  • If outdoors and there is no shelter close by, crouch down with your face away from the wind. Protect your neck with your hands.