Severe thunderstorm warning
Updated
A severe thunderstorm warning is issued by your local National Weather Service office when a thunderstorm is already producing or is expected to produce hail at least 1 inch in diameter or wind gusts of 58 mph or stronger. The warning covers a storm-shaped area and typically lasts 30 to 60 minutes. A watch is different: it is a heads-up for a large region issued hours earlier.
Right now0Severe thunderstorm warnings in effectas of Hail reports by state, today and on record
WeatherTotals issues no alerts or warnings. Official warnings: weather.gov.
Watch vs warning
| Who issues | What it means | Area | Typical length | What to do | |
|---|---|---|---|---|---|
| Watch | Storm Prediction Center in Norman, Oklahoma | Conditions are favorable for severe thunderstorms | Several counties or parts of states | 4 to 8 hours | Be ready and have a plan |
| Warning | Local National Weather Service forecast office | Hail 1 inch or larger or wind gusts of 58 mph or more are occurring or imminent | Storm-shaped polygon, not whole counties | 30 to 60 minutes | Take shelter now |
What counts as severe?
The National Weather Service defines a thunderstorm as severe based on hail and wind, not lightning or tornadoes. Every thunderstorm has lightning, so lightning alone does not meet the threshold. Tornadoes get a separate Tornado Warning. Since August 2021, warnings can also carry a damage-threat tag that describes how intense the storm is.
- A base warning goes out when hail is at least 1 inch (quarter size) or when gusts reach 58 mph (50 knots) or stronger.
- Considerable tag: hail 1.75 inches (golf ball size) or larger, or wind gusts of 70 mph or more.
- Destructive tag: hail 2.75 inches (baseball size) or larger, or wind gusts of 80 mph or more. Phones inside the polygon get Wireless Emergency Alerts only for warnings with this tag.
What should you do during a warning?
- Go inside a sturdy building and stay away from windows.
- Do not shelter under trees.
- If you are driving and can safely reach a sturdy cover like a gas station canopy, pull off the road and park under it.
- If you cannot reach cover, stay in the car and keep away from the windows.
- Stay inside for 30 minutes after the last thunder you hear before heading back out.
How does the warning reach you?
Weather warnings from the National Weather Service are broadcast on NOAA Weather Radio and appear on weather.gov. Local TV and radio stations also carry them. Most phones receive Wireless Emergency Alerts only for destructive-tag warnings, not for base warnings.