US Weather

About US Weather

The National Weather Service (NWS) API provides programmatic access to forecasts, alerts, and observations along with other weather data from the United States government. It is located at api.weather.gov and uses a cache-friendly design that expires content based on the information's life cycle. The API is built on JSON-LD to support machine data discovery, with additional response formats available including GeoJSON, DWML, OXML, CAP, and ATOM, selected through content negotiation headers.

Forecast data is generated at each NWS Weather Forecast Office on a grid of approximately 2.5km x 2.5km resolution. The /points endpoint converts latitude/longitude coordinates into the corresponding grid forecast endpoints, which offer 12-hour period forecasts, hourly forecasts, and raw grid forecast data, along with information about the issuing office, observation stations, and zones for that location.

The service requires a User-Agent header identifying the calling application, with an API key planned as a future replacement. It is free to use for any purpose, with reasonable rate limits in place to prevent abuse; exceeding the limit returns an error that can typically be retried after about 5 seconds. New features are rolled out via feature flags communicated through Service Change Notices, giving developers time to adopt changes before they become default. The API is intended for developers building applications that need access to official US weather forecasts, alerts, and observational data.

Key features

• Provides forecasts, alerts, and observations from the National Weather Service
• Grid-based forecast data at approximately 2.5km x 2.5km resolution
• Supports multiple response formats including GeoJSON, JSON-LD, DWML, OXML, CAP, and ATOM
• Uses content negotiation via Accept headers to select response format
• Feature flags let developers opt into new API features before they become default

Frequently asked questions