Environment Canada
Severe thunderstorm warnings and watches in Canada
A severe thunderstorm warning is about the hail, wind and rain of a thunderstorm; lightning comes with any thunderstorm, warned or not. At yellow, some travel delays, local outages, damage to roofs, fences and trees, and possible flooding; at orange, significant damage to buildings and trees and dangerous flooding; at red, buildings and many trees destroyed. A severe thunderstorm watch says the conditions favour such storms; it can become a warning. A warning for gusts of 130 km/h or more, or hail of 7 cm or more, is also sent to phones through Alert Ready.
Environment and Climate Change Canada issues three kinds of weather alert. A warning: act now, severe weather is happening or will happen, usually 6 to 24 hours ahead (a tornado can come with less than 30 minutes’ notice). An advisory: act now, for weather less severe but still significant — blowing snow, fog, freezing drizzle and frost. A watch: get ready, the conditions favour severe weather, and it may become a warning. Each alert now also has a colour, for the impact expected where you are.
Where it is in force now
No severe thunderstorm warning is in force at the moment. As read at 27 October at 10:01 UTC from the warnings Environment Canada publishes.
What the levels mean
- Yellow
- Weather that may do damage, cause disruption or affect health; moderate, local or short-lived impacts. The most common colour.
- Orange
- Weather likely to do significant damage, cause major disruption or affect health; widespread impacts, or impacts that may last a few days. Uncommon.
- Red
- Very dangerous weather, possibly life-threatening, that will do extreme damage and disruption over a wide area and for a long time. Rare.
The three colours as Environment Canada describes them, in our words.
Environment Canada asks you to read the whole text of every alert, whatever its colour: it says what to expect, where, and what to do.
The last 30 days
The areas warned each day, by level.
- 23 October 2026 — 4 areas4
- 9 October 2026 — 6 areas6
- 8 October 2026 — 7 areas7
- 7 October 2026 — 25 areas25
- 6 October 2026 — 3 areas3
Sources
- Environment Canada: weather alerts (warnings, advisories, watches)
- Environment Canada: colour-coded weather alerts
- Environment Canada: weather impact guides
- Environment Canada: the alerts in force, on its map
Licence of the warnings: Environment and Climate Change Canada · ECCC Data Services End-use Licence 2.1.1