Data sources

• GOES Geostationary Lightning Mapper (GLM) — Lightning over the Americas: the nearest-strike distance, the map, alerts, history and the monthly report.
• Meteosat Third Generation Lightning Imager (MTG-LI) — Lightning over Europe, Africa and the Middle East — the same features as GLM.
• National Weather Service hourly forecast — The storm forecast in the app (thunderstorm hours, rain chance) for places in the United States (in the app).
• MET Norway Locationforecast — The storm forecast in the app everywhere outside the United States (in the app).
• RainViewer radar composite — The precipitation radar in the app (in the app).
• NOAA NCEI Storm Events Database — The notable lightning events since 2015 on US city pages.
• Copernicus DEM GLO-90 (WorldDEM™-90) — Ground elevation and the terrain label on city pages.
• Mapbox maps with OpenStreetMap data — The map under the lightning, in the app and on this site.

Run by

NOAA (US National Oceanic and Atmospheric Administration)

Used for

Lightning over the Americas: the nearest-strike distance, the map, alerts, history and the monthly report

What it measures

Brief flashes of light at the cloud tops, seen from GOES-19 and GOES-18 in geostationary orbit. It sees total lightning — flashes inside clouds as well as those that reach the ground — and reports each flash as one point near its centre.

Coverage

North and South America and the nearby oceans, day and night

Timing

New data about every 20 seconds; a flash usually reaches the app within about 2 minutes (the free tier adds a 1–2 minute delay)

Limits

Places a flash within roughly 8–14 km, so every distance we show is rounded. It cannot say whether a flash touched the ground, or where exactly.

Licence

US government work, public domain. Credited as “NOAA GOES-R GLM”.

Source

www.goes-r.gov/spacesegment/glm.html

Run by

EUMETSAT

Used for

Lightning over Europe, Africa and the Middle East — the same features as GLM

What it measures

The same kind of optical total-lightning detection as GLM, from a European geostationary satellite.

Coverage

Europe, Africa, the Middle East and the eastern Atlantic

Timing

Up to about 10 minutes from flash to app: EUMETSAT publishes the flashes in batches

Limits

The same 8–14 km location accuracy and the same flash-not-ground-strike limit as GLM.

Licence

Creative Commons Attribution 4.0 (CC BY 4.0). Credited as “Contains EUMETSAT MTG-LI data”.

Source

www.eumetsat.int/meteosat-third-generation

Run by

NOAA National Weather Service (NWS)

Used for

The storm forecast in the app (thunderstorm hours, rain chance) for places in the United States

What it measures

The official hourly forecast for the NWS forecast grid cell around a place.

Coverage

The United States and its territories

Timing

Updated by the NWS through the day; the app caches it for 30 minutes

Limits

A forecast for an area and an hour — never a promise about a strike at one spot.

Licence

US government work, public domain. Credited as “NWS”.

Source

www.weather.gov/documentation/services-web-api

Run by

Norwegian Meteorological Institute

Used for

The storm forecast in the app everywhere outside the United States

What it measures

A global hourly weather forecast, including a thunder symbol per hour.

Coverage

Worldwide

Timing

Updated several times a day; cached for 30 minutes

Limits

Rain chance is often missing outside the Nordic countries, so the app shows the thunder signal on its own there.

Licence

Norwegian Licence for Open Government Data (NLOD) 2.0 and CC BY 4.0. Credited as “MET Norway”.

Source

api.met.no/weatherapi/locationforecast/2.0/documentation

Run by

RainViewer

Used for

The precipitation radar in the app

What it measures

Weather radar images from national networks (including NOAA NEXRAD), combined into one map.

Coverage

Where national radar networks exist; the app says so where there is none (for example southern Africa)

Timing

A new frame about every 10 minutes

Limits

Radar shows rain and snow, never lightning itself.

Licence

RainViewer API terms. Credited as “RainViewer · NOAA/NWS”.

Source

www.rainviewer.com/

Run by

NOAA National Centers for Environmental Information

Used for

The notable lightning events since 2015 on US city pages

What it measures

Reports of lightning deaths, injuries and damage, compiled by the NWS.

Coverage

The United States

Timing

Published with a delay of a few months

Limits

Only events that were reported and caused harm; most strikes never appear in it.

Licence

US government work, public domain. Credited as “NOAA NCEI Storm Events Database”.

Source

www.ncdc.noaa.gov/stormevents/

Run by

European Union and ESA (Copernicus), produced by Airbus Defence and Space from DLR TanDEM-X data

Used for

Ground elevation and the terrain label on city pages

What it measures

Height of the Earth's surface on a 90 m grid, from the TanDEM-X radar satellites.

Coverage

Worldwide land; open ocean counts as sea level

Timing

A fixed 2021 release; read once when the city pages are built

Limits

A surface model: it includes buildings and trees, and one value covers a 90 m cell, so a city's figure is its centre's surface height rather than a surveyed ground level. The organisations in charge of the Copernicus programme by law or by delegation do not incur any liability for any use of the Copernicus WorldDEM™-90.

Licence

Licence for COP-DEM-GLO-90-F Global 90m Full, Free & Open (free for any use, with this credit). Credited as “produced using Copernicus WorldDEM™-90 © DLR e.V. 2010-2014 and © Airbus Defence and Space GmbH 2014-2018 provided under COPERNICUS by the European Union and ESA; all rights reserved”.

Source

registry.opendata.aws/copernicus-dem/

Run by

Mapbox and OpenStreetMap contributors

Used for

The map under the lightning, in the app and on this site

What it measures

Roads, borders, place names and satellite imagery.

Coverage

Worldwide

Timing

Map data updates continuously

Limits

Geographic context only.

Licence

Mapbox terms; OpenStreetMap data under the Open Database License. Credited as “© Mapbox © OpenStreetMap”.

Source

www.mapbox.com/about/maps/

We use primary sources from the agencies that operate the instruments, so you can open the same data yourself. StrikeCast is independent and is not affiliated with, or endorsed by, NOAA, the National Weather Service, EUMETSAT or any agency listed here.

How the distance and the approaching / moving-away trend are worked out from these sources is on the methodology page. Found a source described wrongly? Email support@strikecast.app — see the editorial policy for how corrections are handled.

For safety decisions, follow official warnings from the National Weather Service or your national weather service, and go indoors when you hear thunder.