Tornado watch vs warning: the difference that counts
A watch says conditions are favourable; a warning says one has been detected. The gap between them can be a matter of minutes.
The two alerts use very similar words and mean radically different things. Confusing them is especially costly with tornadoes, because the gap between knowing and needing to act can be minutes.
Watch: prepare and monitor
A tornado watch covers a broad area for several hours and means the atmosphere has what it takes to produce tornadoes. It does not mean one exists.
With a watch active, review where your shelter is, keep shoes and a flashlight nearby, charge phones and stay tuned to radio and sky.
Warning: shelter now
A tornado warning means one has been detected by radar or seen by a spotter. It covers a small area and a short interval.
The response has no intermediate steps: get to shelter, now.
| Watch | Warning | |
|---|---|---|
| What it says | Conditions favourable | Tornado detected |
| Area | Broad | Small |
| Duration | Several hours | Minutes |
| What to do | Prepare and monitor | Shelter immediately |
Why a siren is not enough
Outdoor sirens were designed to warn people in the street. They are not engineered to be heard inside a house with the windows closed, and many communities have none at all.
Relying on the siren has another problem: it does not tell you what is happening or where. A weather radio with automatic county alerts does.
The night-time scenario
A warning at 3 a.m. only helps if something wakes you. The two reliable options are a weather radio programmed for your county and your phone’s emergency alerts enabled, with sound and not on silent.
- The safest place in your house during a tornado As low, as interior and with as few exterior walls as possible. How to pick your shelter depending on the kind of home you live in.
- What to do if a tornado catches you in your car or outdoors A car is one of the worst places to be and an overpass is worse still. What to do when there is no sturdy building anywhere nearby.
Gear that covers this
Products that match what the guide above recommends.
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Weather radio with automatic alerts
It switches itself on when a warning is issued for your county. That is what wakes a family at 3 a.m.
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Helmets for the whole family
Most fatal tornado injuries are head injuries. A bike helmet per person kept in the shelter is one of the most recommended and least applied measures.
Frequently asked questions
What is the difference between a tornado watch and a warning?
A watch means atmospheric conditions favour tornado formation across a broad area for several hours. A warning means one has been detected by radar or spotted, and you need to take shelter immediately.
How much warning time does a tornado warning give?
Lead time is short and variable: often a handful of minutes up to a few tens of minutes. That is why the shelter has to be chosen beforehand, not in the moment.
Does a siren always sound before a tornado?
No. Sirens are designed to warn people who are outdoors, not indoors, and not every community has them. Relying only on a siren is a common mistake.
How do I get warnings while asleep?
With a weather radio with automatic alerts or with your phone's emergency alerts enabled and the volume up. A night-time warning is the scenario with the most casualties.