---
title: "Active aviation SIGMETs"
method: GET
path: "/api/v1/weather/nws/aviation/sigmets"
tags: ["Environment"]
---

# Active aviation SIGMETs

`GET /api/v1/weather/nws/aviation/sigmets`

Return the list of active Significant Meteorological Information (SIGMET) advisories. SIGMETs are issued by ATS units when hazards materialise in controlled airspace: mountain obscuration, icing, turbulence, volcanic ash, and convective activity. Each SIGMET carries a polygon describing the affected airspace, a validity window (typically 2-4 hours), the ATS unit that issued it, and a WMO phenomenon code. Optional filter by `atsu` narrows to a single ATS unit (e.g. `JNU`, `ZAN`). Attribution: NOAA National Weather Service (api.weather.gov).

## Query parameters

- `atsu` string, nullable — ATS unit code (e.g. `JNU`, `ZAN`) to filter the list.

## Response `200`

List of active SIGMETs.

- EnvelopeNwsSigmetsPayload
  - `data` NwsSigmetsPayload, required — Active SIGMETs list response.
    - `count` integer, required — Number of SIGMETs returned.
    - `sigmets` NwsSigmet[], required — SIGMET records.
      - `id` string, nullable — SIGMET identifier.
      - `issue_time` string, nullable — Issue time (ISO 8601).
      - `start` string, nullable — Validity start (ISO 8601).
      - `end` string, nullable — Validity end (ISO 8601).
      - `atsu` string, nullable — ATS unit that issued the SIGMET (e.g. `JNU`, `ZAN`).
      - `sequence` string, nullable — Sequence identifier within the ATS unit's issue cycle.
      - `phenomenon` string, nullable — WMO phenomenon code URI (e.g. `MT_OBSC`, `CONVECTIVE`).
      - `geometry` object, nullable — GeoJSON polygon of the affected airspace.
    - `filters` object, required — Echo of the filter parameters supplied by the caller.
  - `meta` SugraMeta, required — Metadata attached to every /api/v1/* response envelope.
    - `endpoint` string, required — Requested endpoint path.
    - `data_time` string, required — ISO 8601 UTC timestamp of the source data, not of the request.
    - `response_time` string, required — ISO 8601 UTC timestamp when this response was produced.
    - `provider` string, required — API name and version.
    - `source` string, nullable — Identifier of the primary upstream source used for this response.
    - `attribution` string, nullable — Human-readable attribution mandated by an upstream source (e.g. a securities regulator or self-regulatory organization). Present only on responses whose source requires the owner and source to be clearly identified. Do not remove or alter it when using the response.
    - `fallback_used` boolean, nullable — True when the primary source failed and a fallback produced the data.
    - `fallback_chain` string[], nullable — Ordered list of sources attempted, in the order they were tried.
    - `cached` boolean, nullable — True when this response was served from the internal cache.
    - `stale` boolean, nullable — True when the cached response was returned after the upstream rate-limited or errored. Clients can use this to detect degraded data.

## Other responses

- `401` — Missing or invalid `x-api-key` header. JSON body with a stable `code` distinguishing `missing_api_key` (no header sent) from `invalid_api_key` (header sent, key not accepted); any other 401 source carries the generic `unauthorized` with its detail as `reason`. Plus `hint`. `plan` is always null on 401 - an unauthenticated request has no plan; quota exhaustion is 429, not 401.
- `422` — Validation Error
- `429` — Daily rate limit exceeded. Check `X-RateLimit-Reset` for the next window.
- `503` — Upstream source is temporarily unavailable. Retry after a short delay.

---

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