Marine Weather API

Hourly wave forecasts at 5 km resolution

Select Coordinates or City

Hourly Marine Variables

Daily Marine Variables (*)

* Parameter timezone is mandatory

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API Documentation

The API endpoint /v1/marine accepts a geographical coordinate, a list of weather variables and responds with a JSON hourly marine weather forecast for 7 days. Time always starts at 0:00 today. All URL parameters are listed below:

Parameter Format Required Default Description
latitude, longitude Floating point Yes Geographical WGS84 coordinate of the location
hourly String array No A list of weather variables which should be returned. Values can be comma separated, or multiple &hourly= parameter in the URL can be used.
daily String array No A list of daily weather variable aggregations which should be returned. Values can be comma separated, or multiple &daily= parameter in the URL can be used. If daily weather variables are specified, parameter timezone is required.
timeformat String No iso8601 If format unixtime is selected, all time values are returned in UNIX epoch time in seconds. Please note that all timestamp are in GMT+0! For daily values with unix timestamps, please apply utc_offset_seconds again to get the correct date.
timezone String No GMT If timezone is set, all timestamps are returned as local-time and data is returned starting at 00:00 local-time. Any time zone name from the time zone database is supported. If auto is set as a time zone, the coordinates will be automatically resolved to the local time zone.
past_days Integer (0-2) No 0 If past_days is set, yesterday or the day before yesterday data are also returned.
start_date
end_date
String (yyyy-mm-dd) No The time interval to get weather data. A day must be specified as an ISO8601 date (e.g. 2022-06-30).
length_unit String No metric Options metric and imperial
cell_selection String No sea Set a preference how grid-cells are selected. The default land finds a suitable grid-cell on land with similar elevation to the requested coordinates using a 90-meter digital elevation model. sea prefers grid-cells on sea. nearest selects the nearest possible grid-cell.
apikey String No Only required to commercial use to access reserved API resources for customers. The server URL requires the prefix customer-. See pricing for more information.

Additional optional URL parameters will be added. For API stability, no required parameters will be added in the future!

Hourly Parameter Definition

The parameter &hourly= accepts the following values. Most weather variables are given as an instantaneous value for the indicated hour. Some variables like precipitation are calculated from the preceding hour as an average or sum.

Variable Valid time Unit Description
wave_height
wind_wave_height
swell_wave_height
Instant Meter Wave height of significant mean, wind and swell waves
wave_direction
wind_wave_direction
swell_wave_direction
Instant ° Mean direction of mean, wind and swell waves
wave_period
wind_wave_period
swell_wave_period
Instant Seconds Period between mean, wind and swell waves.
wind_wave_peak_period
swell_wave_peak_period
Instant Seconds Peak period between wind and swell waves.

Daily Parameter Definition

Aggregations are a simple 24 hour aggregation from hourly values. The parameter &daily= accepts the following values:

Variable Unit Description
wave_height_max
wind_wave_height_max
swell_wave_height_max
Meter Maximum wave height on a given day for mean, wind and swell waves
wave_direction_dominant
wind_wave_direction_dominant
swell_wave_direction_dominant
° Dominant wave direction of mean, wind and swell waves
wave_period_max
wind_wave_period_max
swell_wave_period_max
Seconds Maximum wave period of mean, wind and swell
wind_wave_peak_period_max
swell_wave_peak_period_max
Seconds Maximum peak period between wind and swell waves.

JSON Return Object

On success a JSON object will be returned.

      

  "latitude": 52.52,
  "longitude": 13.419,
  "elevation": 44.812,
  "generationtime_ms": 2.2119,
  "utc_offset_seconds": 0,
  "timezone": "Europe/Berlin",
  "timezone_abbreviation": "CEST",
  "hourly": {
    "time": ["2022-07-01T00:00", "2022-07-01T01:00", "2022-07-01T02:00", ...],
    "wave_height": [1, 1.7, 1.7, 1.5, 1.5, 1.8, 2.0, 1.9, 1.3, ...]
  },
  "hourly_units": {
    "wave_height": "m"
  },

      
    
Parameter Format Description
latitude, longitude Floating point WGS84 of the center of the weather grid-cell which was used to generate this forecast. This coordinate might be a few kilometers away from the requested coordinate.
generationtime_ms Floating point Generation time of the weather forecast in milliseconds. This is mainly used for performance monitoring and improvements.
utc_offset_seconds Integer Applied timezone offset from the &timezone= parameter.
timezone
timezone_abbreviation
String Timezone identifier (e.g. Europe/Berlin) and abbreviation (e.g. CEST)
hourly Object For each selected weather variable, data will be returned as a floating point array. Additionally a time array will be returned with ISO8601 timestamps.
hourly_units Object For each selected weather variable, the unit will be listed here.
daily Object For each selected daily weather variable, data will be returned as a floating point array. Additionally a time array will be returned with ISO8601 timestamps.
daily_units Object For each selected daily weather variable, the unit will be listed here.

Errors

In case an error occurs, for example a URL parameter is not correctly specified, a JSON error object is returned with a HTTP 400 status code.

      

  "error": true,
  "reason": "Cannot initialize WeatherVariable from invalid String value tempeture_2m for key hourly"

      
    

Citation & Acknowledgement

Generated using ICON Wave forecast from the German Weather Service DWD.

All users of Open-Meteo data must provide a clear attribution to DWD as well as a reference to Open-Meteo.