Environment Canada: Warning vs Watch vs Special Weather Statement
ECCC's alerts run on a ladder of urgency. Here's precisely what a statement, advisory, watch and warning each mean — and the one distinction you must not confuse.
Environment and Climate Change Canada (ECCC) issues alerts on a ladder of urgency. A special weather statement is early, low-key notice that something unusual may be developing. A watch means conditions are favourable for severe weather — be prepared. A warning means severe weather is happening or imminent — take action now. In short: statement = heads-up, watch = get ready, warning = act.
How ECCC's alert ladder works
ECCC uses a graduated system so the wording itself tells you how urgent the situation is and what you should do. From least to most urgent, the four public-alert types are the special weather statement, the advisory, the watch and the warning. The key mental model is that a watch is about likelihood ("the ingredients are coming together"), while a warning is about certainty and timing ("it's here or about to be"). Get that distinction right and the rest follows.
What is a special weather statement?
A special weather statement is the gentlest alert on the ladder. ECCC issues one to flag developing or unusual weather that could cause concern but does not yet meet — and may never meet — the criteria for a watch or warning. Think of it as the forecaster thinking out loud several days ahead of a possible storm, an early-season cold snap, or a pattern with unusually high uncertainty. It asks for awareness, not action. Many special weather statements are later upgraded to a watch or warning; many others simply expire when the threat fades.
What is an advisory?
An advisory sits just above the statement. ECCC issues one for weather that is expected to cause general inconvenience or nuisance — and can be hazardous if you are not careful — but is not severe enough to warrant a full warning. Blowing-snow advisories, fog advisories and frost advisories are typical examples. An advisory says: this will affect your day and could catch you out, so take sensible precautions.
What is a weather watch?
A watch is issued when conditions are favourable for a severe-weather event, but its timing, track or occurrence is still uncertain. It is an alert that a warning may become necessary. The classic examples are the severe thunderstorm watch, the tornado watch and the winter storm watch. A watch typically covers a broader area and a longer window than the eventual warning, because forecasters can see the potential before they can pin down exactly where and when it will hit. Your job during a watch is to prepare: know where you would shelter, keep an eye on updates, and be ready to act if a warning follows.
What is a weather warning?
A warning is the top of the ladder: severe weather is occurring or imminent, and it poses a threat to safety or property. This is the signal to take action now — get indoors, get off the road, or move to shelter, depending on the hazard. ECCC issues warnings against defined criteria that vary by region and season. Representative thresholds include:
| Warning | Typical trigger (varies by region) |
|---|---|
| Rainfall | ~25 mm in 1 hour or ~50 mm in 24 hours |
| Snowfall | ~15 cm or more within 12 hours |
| Severe thunderstorm | Wind gusts ≥90 km/h, hail ≥2 cm, and/or torrential rain |
| Wind | Sustained ~70 km/h or gusts ~90 km/h |
| Blizzard | Winds ≥40 km/h with visibility ≤400 m in snow for several hours |
| Extreme cold | Wind chill around −40 (colder in the far North) |
| Heat | Often around a humidex of 40, with warm overnight lows |
These figures are illustrative: ECCC publishes region-specific criteria because 15 cm of snow is routine in Quebec but exceptional on Vancouver Island, and a −40 wind chill means something different in Toronto than in Iqaluit.
Watch versus warning: the difference that matters
If you remember one thing, make it this pair. A watch means "conditions are favourable — be prepared." A warning means "it's happening or about to — take action." A tornado watch says the atmosphere could produce tornadoes across a region this afternoon; a tornado warning says a tornado has been detected or is imminent for a specific area right now. Confusing the two is the most common and most dangerous mistake people make with weather alerts.
| Alert | What it means | What to do |
|---|---|---|
| Special weather statement | Unusual weather may be developing | Stay aware |
| Advisory | Weather that will inconvenience or catch you out | Take precautions |
| Watch | Conditions favourable for severe weather | Be prepared to act |
| Warning | Severe weather occurring or imminent | Take action now |
Where to read ECCC alerts — and how to add confidence
The authoritative source is ECCC itself: the public-alerts map on weather.gc.ca, the Alert Ready system that pushes the most serious warnings to phones, TV and radio, and the WeatherCAN app. Always treat ECCC as the last word on whether an alert is in force — no third party should override an official warning.
What model comparison adds is lead time and context. Because a watch is fundamentally about how likely a severe set-up is, seeing whether the models agree tells you how seriously to take it. checkweather.io lines up ECCC's GEM against ECMWF, the GFS and ICON and turns their agreement into a forecast-confidence score, with an accuracy scoreboard grading each model against what actually verified. When a severe thunderstorm watch is out and all four models agree on the set-up, that is a watch to respect; when they disagree, you will know the situation is still genuinely up in the air — while still deferring to ECCC's official warning when it comes.