Forecasts are created at each NWS Weather Forecast Office (WFO) on their own grid definition, at a resolution of about 2.5km x 2.5km. The API endpoint for the 12h forecast periods at a specific grid location is formatted as:

	https://api.weather.gov/gridpoints/{office}/{gridX},{gridY}/forecast

For example: https://api.weather.gov/gridpoints/TOP/31,80/forecast

To obtain the grid forecast for a point location, use the /points endpoint to retrieve the current grid forecast endpoint by coordinates:

	https://api.weather.gov/points/{latitude},{longitude}

For example: https://api.weather.gov/points/39.7456,-97.0892

This will provide the grid forecast endpoints for three format options in these properties:

• forecast - forecast for 12h periods over the next seven days
• forecastHourly - forecast for hourly periods over the next seven days
• forecastGridData - raw forecast data over the next seven days

Note: at this time coastal marine grid forecasts are only available from the forecastGridData property.

Applications may cache the grid for a location to improve latency and reduce the additional lookup request; however, it is important to note that while it generally does not occur often, the gridX and gridY values (and even the office) for a given coordinate may occasionally change. For this reason, it is necessary to check back to the /points endpoint periodically for the latest office/grid mapping.

The /points endpoint also contains information about the issuing office, observation stations, and zones for a given point location.

The forecast can be formatted as DWML for the /forecast and /forecast/hourly endpoints. There is no DWML specification for point lookups, so you first need to use the JSON-only /point endpoint described in the previous question to convert the location to a grid. Once you know the full gridpoint url for the forecast or hourly forecast, you can set the Accept header described in the overview to request the DWML format.

• application/vnd.noaa.dwml+xml

For example: https://api.weather.gov/gridpoints/TOP/31,80/forecast

Note! Please see below for current issues with the DWML format.

The following are missing from the /forecast endpoint

• The conditions-icon > icon-link URL will point to the icon provided by the API
• The parameters > temperature for type "heat index"

The following changes are new from the previous MapClick Point Forecast DWML

• The XML header specifying the XML version and encoding
• The location > height node includes attribute for "unit"
• The location > description node will always be location > area-description
• The wordedForecast node attribute for "wordGenerator" has an updated value

The API /forecast/hourly endpoint incorrectly returns the 12-hour Forecast DWML in the Hourly Forecast DWML structure. It cannot effectively be used to obtain hourly weather data.

The API has a robust selection of filters for alerts. A common request is all active alerts for a state:

	https://api.weather.gov/alerts/active?area={state}

For example: https://api.weather.gov/alerts/active?area=KS

The /alerts/active endpoint redirects internally to the root /alerts endpoint with the "active=true" parameter. Please review the "Specification" tab above for all the filter options. For important details about filtered alerts requests according to county or zone UGC, please review our Alerts Geolocation Guide.

For additional details on the format of an alert's content, please see the CAP documentation.

The /alerts endpoint contains alerts issued over the past seven days. For an official archive of NWS CAP alerts, please reach out to the National Centers for Environmental Information (NCEI).