National Weather Service United States Department of Commerce

Ophelia Impacting the East; Heavy Rainfall and Severe Threats for the Center of the Nation

Heavy rain, gusty winds, storm surge, high surf and rip currents that could be life threatening, will affect the Mid-Atlantic through this weekend. For the center of the nation, a cold front will focus showers and thunderstorms, some severe with excessive rainfall and flash flooding, through the weekend. Meanwhile, much cooler temperatures and a wet weather pattern enters the Pacific Northwest. Read More >


The National Weather Service (NWS) API allows developers access to critical forecasts, alerts, and observations, along with other weather data. The API was designed with a cache-friendly approach that expires content based upon the information life cycle. The API is based upon of JSON-LD to promote machine data discovery.

The API is located at:

Operational issues should be reported to

General use questions can be asked on the API github site.


All of the information presented via the API is intended to be open data, free to use for any purpose. As a public service of the United States Government, we do not charge any fees for the usage of this service, although there are reasonable rate limits in place to prevent abuse and help ensure that everyone has access. The rate limit is not public information, but allows a generous amount for typical use. If the rate limit is execeed a request will return with an error, and may be retried after the limit clears (typically within 5 seconds). Proxies are more likely to reach the limit, whereas requests directly from clients are not likely.

Content Negotiation

The new API will use headers to modify the version and format of the response. Every request, either by browser or application, sends header information every time you visit any website. For example, a commonly used header called "UserAgent" tells a website what type of device you are using so it can tailor the best experience for you. No private information is shared in a header, and this is a standard practice for all government and private sites. Developers can override these headers for specific purposes (see the "API Specifications" tab for more information). You can get full details by visiting the header field definitions page at the World Wide Web Consortium site.

  • Authentication
  • Format the response
  • Request new features


A User Agent is required to identify your application. This string can be anything, and the more unique to your application the less likely it will be affected by a security event. If you include contact information (website or email), we can contact you if your string is associated to a security event. This will be replaced with an API key in the future.

User-Agent: (,


Endpoints typically have a GeoJSON default format, given the inclusion of geometry data. See the Specification tab for details on each endpoint. Below are common formats available by the API.

  • GeoJSON: application/geo+json
  • JSON-LD: application/ld+json
  • DWML: application/vnd.noaa.dwml+xml
  • OXML: application/vnd.noaa.obs+xml
  • CAP: application/cap+xml
  • ATOM: application/atom+xml
Accept: application/cap+xml


The API will use feature flags to make new features available to consumers. The available feature flags will be noted on the "Updates" tab on this page. The feature flag will be communicated through a Service Change Notice (SCN) allowing developers a period to adopt the flag if the change impacts their applications. Once the adoption window expires, the feature will be made default. Developers can then remove the flag at their convenience.

Feature-Flag: forecast_temperature_qv

Outage Information

Information on outages is generally communicated through Administrative messages sent by National Center of Environmental Prediction's (NCEP's) Senior Duty Meteorologist (SDM). These are sent via WMO id NOUS42 KWNO and product identifier ADASDM.

Examples of using the API

The API uses linked data to allow applications to discover content. Similar to a web site that provides HTML links to help users navigate to each page, linked data helps applications navigate to each endpoint. You may also review the OPEN API specification on the "Specification" tab on this page, or directly using the specification endpoint (that is also used to create the tab presentation):


How do I get the forecast?

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:{office}/{gridX},{gridY}/forecast

For example:,80/forecast

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

For example:,-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

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.


How do I get alerts?

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

For example:

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).



The information on this page is updated regularly.

Feature Flags

There are currently no feature flags.

Known Issues

Before contacting us, please review the following list of issues that have been identified for a future update.

  • Radar station information (/radar endpoints) performance is unreliable.
  • The zones endpoint has a constraint on the number of zones able to be returned at once. Requesting many zones will result in an error.
  • The gridpoints endpoint returns a 500 error. Retrying the request generally returns valid data.
  • The gridpoints/forecast and gridpoints/forecast/hourly endpoints do not work for WFO AFC (site id AER and ALU on the gridpoints endpoint).
  • The gridpoints endpoint is known to return a 503 error for long periods with forecasts for ABQ, AFG, EWX, LSX, MAF, TSA, and UNR.
  • The observations endpoints may show null values for temperature and precipitation at some stations when the MADIS source has data.
  • Precipitation values in the observations endpoints are rounded down to the nearest centimeter (less than 0.4" may be improperly rounded down to 0).
  • Forecast endpoints may return a bad icons link when PoP = 0%. Removing the ",0" returns the proper icon.

Updated 8/24/2023

Upstream Issues/Changes

The following issues are related to upstream sources of the API, and are not an API bug.

  • Delayed observations

    Observations may be delayed up to 20 minutes from MADIS, the upstream source.



The following issues have been recently resolved:

  • 25 Feb 2022: The gridpoints endpoint no longer serves stale data. For this endpoint we currently are not returning the Last-Modified header. In addition, the If-Modified-Since header is also being ignored for gridpoints request.

  • 5 Jul 2022: Observations are again being sorted in chronological order.

  • 16 Mar 2023: The points endpoint no longer returns gridpoints URLs that are off by +1,+1.



Important! Only the following endpoints are considered operational. Changes to operational endpoints are subject to PNS and SCN notices. All other endpoints are subject to change without notice.

  • /alerts/*

Note: All times generated by the API are in ISO-8601 format.