Potential Thunderstorms

  • Stay up to date with latest local weather forecasts (for example, The Weather Channel, local radio/TV stations/websites, The Weather Network, Environment Canada, Weather-One-On-One).
  • What to look for and/or listen for:
    • Severe Thunderstorm Watch:
      • When conditions are favourable for the development of severe thunderstorms with one or more of the following conditions:
      • Wind gusts of 90 km/hr or greater
      • Hail of two centimeters (cm) or larger in diameter
      • Heavy rainfall
    • Severe Thunderstorm Warning:
      • 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/hr or greater
      • Hail of two centimeters (cm) or larger in diameter
      • Heavy rainfall
  • Contact: WEATHER-ONE-ON-ONE at 1-900-565-5555. This is a user-pay consultation service from Environment Canada that puts you in touch with a meteorologist weekdays from 5:00 am -9:00 p.m. Charges of $2.99 per minute, plus taxes, will be added directly to your telephone bill.
  • Note: Environment Canada does NOT specifically warn for lightning.

When Outside

  • Observations:
    • What to look for: Large dark clouds, gusty winds, heavy rain/hail, lightning
    • What to listen for: Thunder: (Thunder is caused by lightning)
  • Canadian Lightning Danger Maps: Use a hand-held mobile device to monitor threats using Canadian Lightning Danger maps. When the red danger zones are in or are approaching your location, lightning is striking and there is immediate danger if outdoors. Go to a safe shelter. The interval between maps is 10 minutes. Refresh your browser to ensure you have the most current map.