ECMWF Weather Forecast API

Global High Frequency Forecasts at 0.4° resolution

Select Coordinates or City

3-Hourly Weather Variables


Usage License

Preview and API URL

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Data Source

This API uses open-data ECMWF Integrated Forecast System IFS. ECMWF IFS models run every 6 hours at 9 km resolution, but only 0.4° grid spacing (~44 km) is available as open data with a limited number of weather variables at 3-hourly intervals. As soon as ECWMF includes additional data, they will be made available in this API.

For hourly and high-resolution data (up to 1 km) try our forecast API which combines multiple models.

Weather Model Region Spatial Resolution Temporal Resolution Forecast Length Update frequency
IFS Global 0.4° (~44 km) 3-Hourly 10 days Every 6 hours

API Documentation

The API endpoint /v1/ecmwf accepts a geographical coordinate, a list of weather variables and responds with a JSON 3-hourly weather forecast for 10 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
elevation Floating point No The elevation used for statistical downscaling. Per default, a 90 meter digital elevation model is used. You can manually set the elevation to correctly match mountain peaks. If &elevation=nan is specified, downscaling will be disabled and the API uses the average grid-cell height.
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.
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 note that all time is then in GMT+0! 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, yesterday or the day before yesterday data are also returned.
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).
cell_selection String No land 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 and average or sum.

Variable Valid time Unit Description
precipitation Preceding hour sum mm (inch) Total precipitation (rain, showers, snow) sum of the preceding hour
snowfall Preceding hour sum cm (inch) Snowfall amount of the preceding hour in centimeters. For the water equivalent in millimeter, divide by 7. E.g. 7 cm snow = 10 mm precipitation water equivalent. Snowfall amount is not provided by ECMWF directly, instead it is approximated based on total precipitation and temperature
runoff Preceding hour sum mm (inch) Execess rain that is not absorbed by the soil
weathercode Instant WMO code Weather condition as a numeric code. Follow WMO weather interpretation codes. See table below for details. Weather code is calculated from cloud cover analysis, precipitation and snowfall. As ECMWF IFS has barely no information about atmospheric stability, estimation about thunderstorms is not possible.
cloudcover Instant % Total cloud cover as an area fraction. Calculated as a weighted function from low, mid and high level clouds.
cloudcover_low Instant % Low level clouds and fog up to 3 km altitude. In case of ECMWF IFS it is based on relative humidity on pressure levels 1000, 925 and 850 hPa.
cloudcover_mid Instant % Mid level clouds from 3 to 8 km altitude. In case of ECMWF IFS it is based on relative humidity on pressure levels 700 and 500 hPa.
cloudcover_high Instant % High level clouds from 8 km altitude. In case of ECMWF IFS it is based on relative humidity on pressure levels 300, 250 and 200 hPa.
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_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 meter Geopotential height on different atmospheric pressure levels
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_1000hPa, ...
Instant ° Wind direction at 10 meters above ground and different pressure levels.
relative_humidity_1000hPa, ... Instant % Relative humidity at atmospheric pressure levels. Unfortunately, 2 meter relative humidity is unavailable.
cloudcover_1000hPa, ... Instant % Cloud cover at the specified pressure level. Cloud cover is approximated based on relative humidity using Sundqvist et al. (1989)
specific_humidity_1000hPa, ... Instant g/kg Specific humidity at different atmospheric pressure levels
atmosphere_relative_vorticity_1000hPa, ... Instant s⁻¹ Relative vorticity at different atmospheric pressure levels
divergence_of_wind, ... Instant s⁻¹ Differgence of wind at different atmospheric pressure levels

JSON Return Object

On success a JSON object will be returned.


  "latitude": 52.52,
  "longitude": 13.419,
  "generationtime_ms": 2.2119,
  "timezone": "Europe/Berlin",
  "timezone_abbreviation": "CEST",
  "hourly": {
    "time": ["2022-07-01T00:00", "2022-07-01T01:00", "2022-07-01T02:00", ...],
    "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 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.
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.


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"


Weather variable documentation

WMO Weather interpretation codes (WW)

Code Description
0 Clear sky
1, 2, 3 Mainly clear, partly cloudy, and overcast
45, 48 Fog and depositing rime fog
51, 53, 55 Drizzle: Light, moderate, and dense intensity
56, 57 Freezing Drizzle: Light and dense intensity
61, 63, 65 Rain: Slight, moderate and heavy intensity
66, 67 Freezing Rain: Light and heavy intensity
71, 73, 75 Snow fall: Slight, moderate, and heavy intensity
77 * Snow grains
80, 81, 82 * Rain showers: Slight, moderate, and violent
85, 86 * Snow showers slight and heavy
95 * Thunderstorm: Slight or moderate
96, 99 * Thunderstorm with slight and heavy hail

(*) Showers and thunderstorm forecast not available with ECMWF IFS

This service is based on data and products of the European Centre for Medium-Range Weather Forecasts (ECMWF). Source ECMWF does not accept any liability whatsoever for any error or omission in the data, their availability, or for any loss or damage arising from their use.