What "Closest Lightning Strike" Actually Means
Lightning detection systems report individual flashes as point coordinates in space and time. The "closest strike to me" is the lightning flash with the smallest great-circle distance from your current latitude and longitude that was detected within a recent time window — typically the last 30 minutes for tactical safety decisions, or the last 24 hours for situational awareness about today's storm activity.
Two factors matter: distance and recency. A strike 8 miles away from 2 minutes ago is operationally relevant; a strike 0.2 miles away from 4 hours ago is a historical curiosity. Useful tools answer both at once.
Three Ways to Find the Closest Strike
1. Use a real-time lightning app
A lightning tracker app uses your device GPS to query a lightning detection feed for the nearest recent strike. Lightning Tracker uses the NOAA GOES-19 Geostationary Lightning Mapper (GLM) — a satellite-based sensor that detects optical pulses from cloud-to-ground and intra-cloud flashes across the entire Western Hemisphere with 30–60 second latency.
Apps return distance in miles or kilometres, bearing (compass direction), and time-since-detection. They typically also show storm tracks — the predicted future position of detected storm cells — so you know whether the nearest strike is moving toward you or away.
2. Browse a state or city lightning map
The fastest desktop check: visit a regional lightning map. Browse our all 50 US state lightning maps or jump straight to a specific area:
- Florida lightning map — the most lightning-prone state
- Texas lightning map
- Oklahoma lightning map
- Colorado lightning map
- Iowa lightning map
Each state and city page now displays a live counter (strikes in the last 24 hours), a recent-strike feed, and an interactive map of the most recent flashes detected by GOES-19 GLM within the area.
3. Estimate by ear (flash-to-bang)
No phone? Count the seconds between the flash and the thunder, divide by 5, and that's the distance in miles. Sound travels through air at roughly 1 mile per 5 seconds, so a 10-second gap means the lightning struck about 2 miles away. See our flash-to-bang guide for the science and a distance table.
What "Close" Means in Safety Terms
The National Weather Service uses the 30-30 rule: if the time between flash and bang is 30 seconds or less (about 6 miles), seek shelter immediately, and stay sheltered for 30 minutes after the last thunderclap.
Why 30 seconds? Lightning can strike up to 10 miles from the edge of a thunderstorm — well beyond where rain is falling. The 6-mile threshold builds in a safety margin: you have minutes to reach a substantial building or hard-topped vehicle before the next strike could hit your immediate area.
What Counts as Shelter
- Substantial building with plumbing and electrical wiring (the metal acts as a Faraday cage).
- Hard-topped vehicle with windows closed (avoid touching metal frame).
- NOT safe: open shelters, picnic pavilions, tents, dugouts, isolated trees, hilltops, open water, beaches, or open fields.
Once indoors, avoid corded phones, plumbing, and plugged-in electronics — see indoor lightning safety for the full list.
How GOES-19 Detects the Closest Strike
The GLM sensor on GOES-19 captures 500 frames per second of the Western Hemisphere, filtered to the 777.4 nm near-infrared wavelength produced by lightning. Each detection is a single pixel that exceeds a brightness threshold. Adjacent pixels in the same frame are clustered into events, events into groups, and groups into flashes — the unit most apps display.
A flash gets a single latitude/longitude (the centroid of the cluster), a timestamp, and an energy estimate. When you ask for the "closest strike to me," the app fetches the most recent flashes near your coordinates and returns the one with the smallest haversine distance. See how GOES-19 GLM detects lightning from space for the full technical detail.
Common Questions
Why does the closest strike sometimes appear over the ocean?
GOES-19 covers oceans as well as land — that's the GLM's biggest advantage over ground-based networks like NLDN. If you live near the coast, a thunderstorm offshore can still produce strikes that show up as your "closest" detected flash. They are no less real for being over water.
How fresh is the data?
GOES-19 GLM Level 2 data is published to NOAA's public S3 bucket every 20 seconds, with typical end-to-end latency of 30–60 seconds from observation to availability. Lightning Tracker polls the bucket continuously, so by the time a flash appears on screen it is usually less than a minute old.
Can I get an alert when a strike happens within X miles?
Yes. Lightning Tracker for iOS sends a push notification when a flash is detected within your configured alert radius. See the lightning alerts guide for setup options including NOAA Weather Radio as a phone-free backup.