Boltwatch

Free lightning alerts for where you are

Choose where you want alerts, then get notified about nearby lightning. You can also turn on alerts for lightning getting closer and weather conditions that favour thunderstorms. No account needed.

Set up lightning alerts
Nearby lightning
Lightning detected in your chosen area, with distance, direction and how long ago.
Lightning getting closer
Recent flashes are closer to your alert area than earlier ones.
Storm outlook
A daytime alert when forecast conditions favour thunderstorms in the next few hours.

Set up alerts on your device

Start with the place you want to follow. Use “Near me” on the map, or open a city lightning map. Open Alerts, choose the alert area and radius, then save your settings.

iPhone and iPad

  1. Open Boltwatch in Safari. In the Share menu, choose “Add to Home Screen”.
  2. Open Boltwatch from the new Home Screen icon.
  3. Choose your area, open Alerts, and allow notifications when asked.

Use an up-to-date version of iOS or iPadOS. Apple explains Home Screen web apps.

Android and computers

  1. Open Boltwatch in a browser that supports web notifications.
  2. Choose your area and open Alerts. Allow notifications when asked, then save your settings.
  3. If notifications are blocked, check both the browser’s site settings and your device’s notification settings.

Check that your device receives a test

After saving, use “Send test” in Alerts. Check for the notification on your device. A saved setting or an accepted test request does not confirm delivery. Focus modes, browser permissions and device settings can stop a notification from appearing.

Alerts can be delayed, and some lightning may be missed. If you hear thunder, go indoors and follow official local weather guidance. Boltwatch does not send an all-clear.

Keep your local map handy

Open a city, state or country map and tap “Save this place”. Your saved places appear above the home map on this browser. You can remove a place at any time. Saving a map does not turn on alerts.

Frequently asked questions

How do lightning alerts work?
Choose your location or a place, then set a radius: 10, 20 or 40 km, or 6, 12 or 25 miles. When the available feeds report lightning in that area, we send a notification to your phone or computer, even when Boltwatch is closed.
How fast are the alerts?
Alerts depend on how quickly lightning reports arrive and your device receives notifications. GOES reports usually arrive about a minute after detection. Meteosat reports cover ten minutes at a time and take longer to arrive. Lightning may have happened several minutes before you get an alert.
Can you predict lightning before it starts?
Storm outlooks show when forecast conditions favour thunderstorms. They don't give an exact chance of lightning or promise advance warning. The getting-closer alert compares recent flashes with earlier ones; it doesn't predict when a storm will reach you.
Can Boltwatch tell me when it is safe outside?
No. Some lightning may be missed, and data feeds can be delayed or unavailable. An empty map doesn't mean it's safe outside, so we don't send all-clear alerts. If you hear thunder, go indoors and follow your local weather service's advice.
Does it work on iPhone?
Yes. On iPhone and iPad, add Boltwatch to your Home Screen from Safari's Share menu, open it from there, and turn on alerts. On Android, Windows, Mac and Linux, use a browser that supports notifications.
Where do alerts work?
GOES covers the Americas and nearby oceans, Meteosat covers Europe and Africa, and FMI supplies ground-sensor reports across the Nordics and Baltics. Coverage and data availability vary, and some flashes may be missed.