Boltwatch
Free lightning alerts for where you are
Get a notification the moment lightning strikes near you, a heads-up when a storm is heading your way, and an all-clear once it's safe to go back outside. It works in your browser, with no app and no account.
Set up lightning alertsStrike nearby
Lightning inside your 6–25 mile zone. Includes distance, direction and how long ago.
Storm approaching
Lightning just outside your zone and closing in, with an estimated arrival time.
Storm outlook
When forecast conditions favour thunderstorms near you in the next few hours.
Frequently asked questions
- How do lightning alerts work?
- Pick your location and a radius (10, 20 or 40 km, or 6, 12 or 25 miles). Our servers watch every lightning strike detected by satellites and ground sensors. When one lands inside your zone, your phone or computer gets a push notification, even if Boltwatch isn't open.
- How fast are the alerts?
- Satellite lightning data reaches us about a minute after a strike, and we check it the moment it arrives. Most alerts land within one to two minutes of the flash.
- Can you predict lightning before it starts?
- We send two kinds of early warning. A storm-approaching alert fires when lightning is close to your zone and getting closer, with a rough arrival time. A storm-outlook alert fires when the forecast atmosphere is unstable enough for thunderstorms (high CAPE, a negative lifted index and a decent chance of rain), usually hours before the first strike.
- What is the all-clear alert?
- Safety guidance is to wait 30 minutes after the last thunder before going back outside. Once there has been no lightning in your zone for 30 minutes, we tell you it's all clear.
- 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. Android, Windows, Mac and Linux work straight from the browser.
- Where do alerts work?
- Anywhere across North, Central and South America and the surrounding oceans, plus the Nordic and Baltic countries. Europe and Africa are coming soon.