Marine Weather API

About the Marine Weather API

An ocean forecast API for any latitude and longitude at sea, returning daily marine conditions as JSON. Send a pair of coordinates and get back the day's high, low and average temperature in Celsius and Fahrenheit, the maximum wind speed in mph and km/h, total precipitation and snow, average humidity, a condition summary, the UV index, and sunrise, sunset, moonrise and moonset times.

It is built for sailing and boating apps, fishing and charter planners, offshore and coastal operations dashboards, and travel tools that need sea conditions by coordinates rather than by city name. One call gives a compact daily summary you can drop straight into a trip plan or a pre-departure checklist.

The Free plan returns the temperatures, maximum wind, precipitation, humidity, condition, UV index and sun and moon times. Paid plans add average visibility in kilometres and miles, the moon phase and the moon's illumination percentage, which matter for night passages and for anglers who plan around the lunar cycle.

How it works

Marine Weather requests a marine forecast for the lat and lon you send from an external weather data provider, and returns the first forecast day, today at that location, as a single flat weather object. Hourly data from the provider is dropped, so the response is a daily summary only. location echoes the coordinates as numbers.

Field names are the provider's day and astronomy values with underscores removed, which is why they read as maxtempc, avghumidity and totalprecipmm. Temperatures are given in both Celsius (c) and Fahrenheit (f): maxtemp* and mintemp* are the day's high and low, and avgtemp* is the daily mean. maxwindmph and maxwindkph give the strongest wind forecast for the day. totalprecipmm, totalprecipin and totalsnowcm are daily totals. avghumidity is a percentage and uv is the UV index. condition is a text summary such as "Moderate or heavy rain shower". sunrise, sunset, moonrise and moonset are local times in 12-hour format, and date is the forecast date in YYYY-MM-DD.

avgviskm and avgvismiles are the day's average visibility. moonphase is a phase name such as "First Quarter", and moonillumination is the illuminated share of the moon from 0 to 100.

Marine coverage is coastal and offshore. A coordinate inland resolves but has no marine forecast, and the call returns a 404 ("No marine forecast is available for this location."). Errors from the provider are passed through with their status and message. Responses are cached for one hour per coordinate pair. On the Free plan avgviskm, avgvismiles, moonphase and moonillumination are removed.

What people use it for

Voyage Route Planning

Commercial shipping dispatchers evaluate maximum wind speeds and precipitation totals along projected corridors to steer vessels away from rough open-sea conditions.

Offshore Fishing Charters

To protect offshore anglers, booking platforms check marine weather conditions, humidity levels, and UV indices before confirming deep-sea reservations.

Regatta Safety Monitoring

When organizing coastal sailing competitions, race committees monitor wind thresholds and precipitation to schedule offshore heats during safe operating windows.

Port Logistics Scheduling

Cargo terminal coordinators track offshore forecast conditions and daylight hours to prepare docking tugs and crane crews for inbound container vessels.

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON

Default REST response

XML

Markup format

YAML

Human-readable

CSV

Tabular export

Beta

GraphQL

Query language

New

MCP

For AI agents

Request parameters — GET /v1/marineweather

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

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curl "https://api.apiverve.com/v1/marineweather?lat=29.48003&lon=-37.62424" \
  -H "x-api-key: YOUR_API_KEY"

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Response — GET /v1/marineweather

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

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{
  "status": "ok",
  "error": null,
  "data": {
    "location": {
      "lat": 29.48003,
      "lon": -37.62424
    },
    "weather": {
      "date": "2026-09-17",
      "avghumidity": 86,
      "condition": "Moderate or heavy rain shower",
      "uv": 5,
      "sunrise": "05:53 AM",
      "sunset": "06:08 PM",
      "moonrise": "12:04 PM",
      "moonset": "10:42 PM",
      "maxtempc": 25.9,
      "maxtempf": 78.6,
      "mintempc": 21.3,
      "mintempf": 70.3,
      "avgtempc": 24.9,
      "avgtempf": 76.8,
      "maxwindmph": 15.4,
      "maxwindkph": 24.7,
      "totalprecipmm": 14.89,
      "totalprecipin": 0.59,
      "totalsnowcm": 0,
      "avgviskm": 7.4,
      "avgvismiles": 4,
      "moonphase": "First Quarter",
      "moonillumination": 42
    }
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 10 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Zero-code embed — one snippet, no backend

Drop an interactive Marine Weather form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.

Changelog — Marine Weather API

Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.

Currently v1Data refreshed realtime