ECMWF Weather Forecast API

API Documentation

The API endpoint /v1/ecmwf accepts a WGS4 coordinate, a list of weather variables and responds with a JSON hourly weather forecast for 7 days. Time always starts at 0:00 today and contains 168 hours. 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 coma separated, or multiple &hourly= parameter in the URL can be used.
temperature_unit	String	No	celsius	If fahrenheit is set, all temperature values are converted to Fahrenheit.
windspeed_unit	String	No	kmh	Other wind speed speed units: ms, mph and kn
precipitation_unit	String	No	mm	Other precipitation amount units: inch
timeformat	String	No	iso8601	If format unixtime is selected, all time values are returned in UNIX epoch time in seconds. Please not that all time is then in UTC! For daily values with unix timestamp, please apply utc_offset_seconds again to get the correct date.
past_days	Integer (0-2)	No	0	If past_days is set, yesterdays or the day before yesterdays data are also returned.

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 and average or sum.

Variable	Valid time	Unit	Description
pressure_msl surface_air_pressure	Instant	hPa	Atmospheric air pressure reduced to sea level (Mean sea level) and actual pressure at surface level
skin_temperature	Instant	°C (°F)	Temperature of the the surface. Depending on the type of surface (e.g. concrete) this temperature can be significantly higher then the 2 meter air temperature
soil_temperature_0_7cm	Instant	°C (°F)	Average temperature of the first soil level 0-7 cm below ground.
total_column_integrated_water_vapour	Instant	kg/m²	Total amount of water in the atmosphere.
temperature_2m temperature_1000hPa, ...	Instant	°C (°F)	Air temperature 2 meter above ground. Additional temperature in the atmopshere are given on different pressure levels.
geopotential_height_1000hPa	Instant	gpm	Geopotential height on different atmospherc pressure levels
windspeed_10m	Instant	gpm	Geopotential height on different atmospherc pressure levels
windspeed_10m windspeed_1000hPa, ...	Instant	km/h (mph, m/s, knots)	Wind speed at 10 meters above ground. Wind speed on 10 meters is the standard level. Additional wind speeds are given on atmospheric pressure levels.
winddirection_10m winddirection_1000hPa, ...	Instant	°	Wind direction at 10 meters above ground and different pressure levels.
relativehumidity_2m relative_humidity_1000hPa, ...	Instant	%	Relative humidity at 2 meters above ground and atmospherc pressure levels
specific_humidity_1000hPa, ...	Instant	g/kg	Specific humidity at different atmospherc pressure levels
atmosphere_relative_vorticity_1000hPa, ...	Instant	s⁻¹	Relative vorticity at different atmospherc pressure levels
divergence_of_wind, ...	Instant	s⁻¹	Differgence of wind at different atmospherc pressure levels

JSON Return Object

On success a JSON object will be returned.


{
  "latitude": 52.52,
  "longitude": 13.419,
  "generationtime_ms": 2.2119,
  "hourly": {
    "time": ["2021-08-28T00:00", "2021-08-28T01:00", "2021-08-28T02:00", ...],
    "temperature_2m": [13, 12.7, 12.7, 12.5, 12.5, 12.8, 13, 12.9, 13.3, ...]
  },
  "hourly_units": {
    "temperature_2m": "°C"
  },
}

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 up to 5 km away.
generationtime_ms	Floating point	Generation time of the weather forecast in milli seconds. This is mainly used for performance monitoring and improvements.
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.

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"
}

ECMWF Weather Forecast API

Select Coordinates or City

Hourly Weather Variables

Settings

API Documentation

Hourly Parameter Definition

JSON Return Object

Errors