Marine weather API
waves, swell and sea stateFor any point at sea or on the coast: how big the waves are, where they come from, how far apart they are, and how much of it is swell and how much is local wind sea.
Free plan · 500 calls a day, no cardRequest
curl -H "X-API-Key: YOUR_KEY" \ "https://atmoatlas.com/api/v1/marine?lat=48.4&lon=-4.5"
const res = await fetch("https://atmoatlas.com/api/v1/marine?lat=48.4&lon=-4.5", { headers: { "X-API-Key": "YOUR_KEY" } }); const data = await res.json();
import requests r = requests.get("https://atmoatlas.com/api/v1/marine", params={"lat": "48.4", "lon": "-4.5"}, headers={"X-API-Key": "YOUR_KEY"}) data = r.json()
Your key goes in the X-API-Key header.
Response
{
"lat": 48.4, "lon": -4.5,
"marine": {
"wave_height_m": 1.91, "wave_direction_deg": 47, "wave_period_s": 7,
"swell_height_m": 0.58, "swell_direction_deg": 47, "swell_period_s": 7,
"wind_wave_height_m": 1.82, "wind_wave_direction_deg": 44, "wind_wave_period_s": 7,
"sea_state": "slight",
"_source": "NOAA GFS-Wave / WaveWatch III (public domain)"
}
}Real response off Brest on 3 November 2026.
Coverage and source
- Coverage
- All oceans and seas covered by the global wave model
- Data
- Total waves, swell and wind sea: height, direction, period
- Inland
- marine is null with a short note, never a made-up value
- Source
- NOAA GFS-Wave / WaveWatch III (public domain)
What the response contains
| Field | Meaning |
|---|---|
wave_height_m / wave_direction_deg / wave_period_s | Significant height, direction (where the waves come from) and period of all waves. |
swell_height_m / swell_direction_deg / swell_period_s | The long waves formed far away. |
wind_wave_height_m / wind_wave_direction_deg / wind_wave_period_s | The short waves raised by the local wind. |
sea_state | The sea state in words, from calm_glassy through slight, moderate and rough to very_high (WMO scale). |
Parameters
| Parameter | Type | Description |
|---|---|---|
lat / lon | float | A point at sea or on the coast. Required. |
What people build with it
Surf apps
Rate a spot from swell height, period and direction.
Sailing and boating
Check the sea before leaving the harbour.
Fishing charters and ferries
Decide whether a trip goes ahead and warn passengers early.
Coastal tourism
Add sea conditions to beach and activity pages.
Frequently asked questions
Do you have water temperature?
Yes, in the forecast endpoint (water_temp_c), from the MUR satellite analysis.
And tides?
Tide times and heights have their own endpoint, /api/v1/tides, with the same key.
Is it free?
The marine endpoint is part of the free plan: 500 calls a day, no card.
Try it with your own key
Create an account in a minute: the key arrives straight away, and the same key opens every other dataset.