What is National Weather Service API?

Forecasts and observations answer different questions. A contract on a daily maximum can specify a station, local reporting day and settlement publication that a nearby forecast grid does not reproduce. Map the intended location to the correct forecast or station endpoint, then preserve the observation’s units and timestamp.

Official guidance covers representations, content negotiation, caching, feature flags, rate limits and outages. Access is free subject to reasonable unpublished rate limits, and requests require a descriptive User-Agent. Follow the access and authentication documentation and validate timestamps, missing observations and update cadence for the research task.

Who it is for

For developers building U.S. weather tools and researchers comparing forecasts with observations.

Features and coverage

Official forecast, alert and observation endpoints
Retrieve documented weather data and select the location, station and data family appropriate to the question.
Machine-readable representations
Use GeoJSON or other documented representations and follow content-negotiation and header requirements.
Operational guidance
Read caching, rate-limit, feature-flag and outage guidance when building a recurring data feed.

Workflows with National Weather Service API

Map the intended weather location

Follow official examples to connect a location to the appropriate forecast or station data, then validate units and timestamps.

Check the contract’s specified source

Compare station, unit and reporting period with the contract’s required source and publication before interpreting a reading as settlement evidence.

Pricing and total cost

Official documentation states access is free, subject to reasonable unpublished rate limits. A descriptive User-Agent is required; follow the documentation for authentication and content negotiation.

Getting started

Before you start: A forecast is not a final observed settlement value. Geographic coverage, station choice, missing readings and update timing all matter; a nearby grid does not reproduce every contract’s reporting day or settlement publication.

Read official examples and the API specification and identify the required location, station and data type.
Use documented headers and caching behavior and validate timestamps and units against the research and contract requirements.

Requests need a descriptive User-Agent and must follow documented authentication and content-negotiation requirements.

Useful links

What to check

A forecast is not a final observed settlement value. Geographic coverage, station choice, missing readings and update timing all matter; a nearby grid does not reproduce every contract’s reporting day or settlement publication.

A closer look