Predict Sea API — free beta
Last updated: 28 September 2026
Derived marine answers for your server: how far the forecast models agree, which model to trust where, the tropical cyclones that are active, and point forecasts — computed from the same forecast releases, by the same code, as the map on this site. JSON over HTTPS, with a key.
What raw feeds don't give you
/v1/compare: the model spread at a position, an agreement level for each valid time and a plain-language verdict ("models already disagree within the first day — low confidence")./v1/auto: the model this site would pick for a layer and an area, with the reason — a finer regional model, or the freshest global run./v1/storms: active tropical cyclones, from NHC advisories and ECMWF tracks, with the ensemble members on request.- The credits each answer's data needs, machine-readable, in every answer: show them and you meet the data licences.
- The same numbers the map shows: one shared code path, pinned by test vectors.
- Coordinates are never logged: a request's position computes the answer and is then forgotten.
Honest limits
- Self-serve keys: 30 requests a minute and 1,000 weight units a UTC day (a point forecast weighs 1, a comparison 1 per model compared). More on request.
- A free beta with no service level: the API can be down, slow or serving a late run.
- Server-side only: the key goes in a header from your server, never in a web page, an app or a URL.
- Point data from the tiled global models only; station observations from US federal stations only.
- Forecast guidance only — not for navigation. Every answer says so, and your users must see it.
When you don't need it
- Raw grids: read the keyless static forecast files this site itself
reads (under
/data/, described by the project's data contract). No key, and they cache well. - Raw point series of the same wave feeds: Open-Meteo serves them, free for non-commercial use.
One example
Every hour of a forecast run between Jersey and the Cotentin coast, from the model this site would pick there:
curl -H "X-Api-Key: $PREDICTSEA_KEY" "https://api.predictsea.com/v1/point?lat=49.25&lon=-1.75"The answer is JSON: data.series holds one row an hour (wind, gusts, waves,
pressure, cloud, rain, temperature), and notice and
attribution say what to show with it. The guide
walks through every endpoint.
Getting a key
Sign up at api.predictsea.com with your email address, a name or organisation and a line on what you will build. Open the link we email you and press Create my key: the key is shown once on the page and a copy is emailed to you — delete that email once the key is stored. One key per person or organisation. If sign-up is paused, write to predictsea@outlook.com.
- Get a key
- Manage a key: replace a lost or leaked key (the old one stops at once), or delete your account.
- Guide and reference
- API terms and what we store about key holders
- Forecast status: how fresh each model's latest run is
For sailors
The website and our apps never use this API, and your position never leaves your device.
API terms · Privacy · Terms & data sources · Forecast status