Official warnings and model forecasts
Official alerts come from the National Weather Service or connected MeteoAlarm member agencies. Only Actual, Public messages are accepted; test messages are excluded. Current conditions and forecasts from Open-Meteo are model data. No forecast-risk algorithm is currently enabled, and forecast values are never converted into official warnings.
Severity and message identity
We preserve the original event name and source instructions. Common Alerting Protocol severity is shown as Extreme, Severe, Moderate, Minor or Unknown. Country systems use different thresholds, so colors are not universal impact guarantees. Certainty and urgency are displayed separately on warning pages. Provider identifiers are normalized into stable internal URLs.
Map geometry
The map displays exact geometries supplied by the providers. Warning markers represent the centers of supplied geometries and are navigation aids, not precise impact locations. Warnings without exact geometry remain in the list. MeteoAlarm bounding boxes are not displayed as exact warning polygons. U.S. city matching uses the NWS point filter; European city matching uses available exact polygons and links back to the country list for other warnings.
Refresh and stale data
U.S. warning responses are cached for two minutes. European warning responses are cached for ten minutes; the EDR source also has an approximately ten-minute delivery delay. Forecast responses are cached for ten minutes, geocoding for one day and air quality for one hour. A request after the cache expires triggers a refresh. Open map views check every two minutes while the tab is visible. Last checked is a retrieval time, not a forecast-model run time.
When a source fails
A failed fetch may use a clearly labeled cached warning snapshot for up to ten minutes for NWS, or twenty minutes for MeteoAlarm. Forecast snapshots may be used for up to one hour. Beyond those limits, data is unavailable. Expired or cancelled messages are removed from the current list. Saved alert pages remain accessible, with expiry or unconfirmed status clearly shown. A partial feed is labeled and its counts must not be treated as complete.
Weather radar
The map can show U.S. composite radar tiles from the Iowa Environmental Mesonet, produced from National Weather Service radar. Radar shows where precipitation was detected. It is not a warning, a rainfall total, or a forecast. Tiles can be delayed, and coverage is weaker in some areas. Warning colors on the same map are a separate layer.
Locations and privacy
Approved city metadata is seeded from GeoNames via Open-Meteo. Search results outside this curated set are not indexed. Browser location is requested only after a button press. BigDataCloud performs consent-driven, client-side reverse geocoding. Coordinates used for forecast caching are rounded to two decimal places, and location lookups are not sent to analytics. This is a useful approximation for weather, not a precise address service.