Weather
Thunderstorm Calculator
Estimate thunderstorm distance from the delay between a seen flash and heard thunder.
Useful only as a non-safety educational timing demonstration
Two-button timing, history and units show the relationship between sound delay and distance.
Keep in mind: Human timing, echoes and identifying the matching flash limit accuracy; do not go outside or delay shelter to obtain a reading, and do not use it as a lightning safety system.
Inside the app
Official product images
What you can do
- Flash/thunder timer
- Metric/imperial estimate
- History and watch controls
Good for
- People discussing the timing principle from a safe place
Consider alternatives for
- Lightning warnings or a safe-distance guarantee
Limitations & considerations
- Captured minimum: iOS 15.6.
- Human timing, echoes and identifying the matching flash limit accuracy; do not go outside or delay shelter to obtain a reading, and do not use it as a lightning safety system.
Privacy & permissions
Review actual device/watch permissions and any sharing; no location tracking is required by the described manual timing workflow itself.
Sources & review notes Updated Nov 12, 2026
Reviewed by iApp4Me Editorial Team. Recommendations use the linked documentation and attributed accounts; device observations are identified separately.
- US App Store developer description
Complete description, download price and compatibility metadata captured 2026-11-02.
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