specification: API Commons Rate Limits
specificationVersion: '0.1'
schema: https://raw.githubusercontent.com/api-evangelist/interface-research/main/schema/api-commons.yml#/$defs/RateLimits

provider: AviationWeather.gov (NOAA/NWS Aviation Weather Center)
providerId: aviationweather
created: '2026-05-29'
modified: '2026-05-29'
reconciled: true

tags:
  - Rate Limiting
  - Government
  - Weather
  - Aviation
  - Open Data
  - NOAA NWS

description: >-
  The AviationWeather.gov public Data API is rate-limited per consumer (IP-based,
  no API key required) at 100 requests per minute. In addition, the docs request
  that no single endpoint be polled more frequently than once per minute per
  thread. Most endpoints return a maximum of 400 entries per response. The
  historical depth of the database is up to 15 days. Limits apply uniformly to
  all formats (raw, decoded, json, geojson, xml, iwxxm) and to all endpoints
  including reference data (stations, airports, navaids). Exceeding the limits
  results in temporary access blocks; the docs encourage waiting between
  consecutive requests and caching responses for short windows. No paid tier or
  raise-via-support process is published — the service is funded as a public
  good by NOAA/NWS.

sources:
  - https://aviationweather.gov/data/api/
  - https://aviationweather.gov/data/schema/openapi.yaml
  - https://aviationweather.gov/help/

responseCodes:
  throttled: 429
  invalidInput: 400
  serverError: 500

limits:
  - name: Global request rate per consumer
    scope: IP
    metric: requests_per_minute
    limit: 100
    timeFrame: minute
    notes: >-
      Applies globally to the consumer (identified by source IP since there is
      no API key). Exceeding this returns HTTP 429 and may trigger a temporary
      block. Documented at aviationweather.gov/data/api/.

  - name: Per-endpoint polling cap
    scope: IP/endpoint/thread
    metric: requests_per_minute
    limit: 1
    timeFrame: minute
    notes: >-
      No single endpoint should be consumed more frequently than once per
      minute from a single thread. This is the recommended minimum interval
      between calls to the same path from the same client thread.

  - name: Response entry cap
    scope: response
    metric: varies
    limit: '400 entries per response'
    notes: >-
      Most endpoints return at most 400 records per response. Use bbox/ids
      narrowing or pagination via temporal parameters (date, hours, age) to
      stay within the cap.

  - name: Historical depth
    scope: dataset
    metric: varies
    limit: '15 days'
    notes: >-
      The weather database currently allows access to up to the previous
      15 days of data. Older data is not available via this API and must be
      obtained from NOAA archives (NCEI).

policies:
  - name: No authentication
    description: >-
      The API does not require an API key. Limits are enforced per source IP,
      so consumers behind NAT or shared egress IPs share quota.

  - name: Wait between requests
    description: >-
      The provider recommends waiting between consecutive requests rather than
      issuing tight loops. Combined with the 1 req/min per-endpoint
      recommendation, this favors batched polling over fan-out.

  - name: Cache short-window results
    description: >-
      METARs typically update at 5-10 minute intervals (or on SPECI events);
      TAFs at 6-hour intervals plus amendments. Caching responses for at least
      one minute is appropriate and reduces load.

  - name: No paid tier
    description: >-
      There is no raise-via-support or paid uplift. Consumers needing higher
      throughput should use NOAA WIFS (Weather Information For System) or FAA
      SWIM for operational bulk distribution.

  - name: Retry on 429
    description: >-
      On HTTP 429, back off for at least one minute before retrying. There is
      no documented Retry-After header at this time, so use a fixed minimum
      backoff of 60 seconds with jitter.

  - name: Use appropriate selector
    description: >-
      Prefer `ids` (ICAO list) or `bbox` (bounding box) to limit returned
      records rather than scanning all data and filtering client-side.
      `@<state>` selectors (e.g. `@KS`) return all stations in a U.S. state.

  - name: Public domain output
    description: >-
      Output data is U.S. Government Work (public domain) per the NWS
      disclaimer. Attribution to NOAA/NWS/AWC is encouraged but not legally
      required.