The API makes use of MET Nordic weather models exclusively for North Europe, offering exceptional
short-term weather forecasts with hourly updates and 1 km resolution. However, for longer
forecasts of up to 16 days, the generic Weather Forecast API transparently combines
MET Nordic with other weather models to take advantage of hourly updates.
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Data Source
This API uses local weather models from the Norwegian Meteorological Institute. The MET Nordic dataset is derived from the 2.5 km MetCoOp ensemble model with ECMWF initialization. With post-processing based on measurement & radar and with updates every hour, the short-term forecast performance skill should be high.
Unfortunately, only 2.5 days of forecast are available. The Open-Meteo weather forecast API automatically uses MET Nordic in combination with larger scale models to offer a 7 days forecast.
| Weather Model | Region | Spatial Resolution | Temporal Resolution | Forecast Length | Update frequency |
|---|---|---|---|---|---|
| MET Nordic | Norway, Denmark, Sweden, Finland | 1 km | Hourly | 2.5 days | Every hour |
API Documentation
The API endpoint /v1/metno accepts a geographical coordinate, a list of weather variables and responds with a JSON hourly weather forecast for 2.5 days. Time always starts at 0:00 today. Data is only available in the Scandinavian region. 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. | |
| current_weather | Bool | No | false | Include current weather conditions in the JSON output. |
| 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. |
| 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). | |
| 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 |
| pressure_msl surface_pressure | Instant | hPa | Atmospheric air pressure reduced to sea level (Mean sea level) and actual pressure at surface level |
| temperature_2m | Instant | °C (°F) | Air temperature at 2 meters above ground |
| relativehumidity_2m | Instant | % | Relative humidity at 2 meters above ground |
| dewpoint_2m | Instant | °C (°F) | Dew point temperature at 2 meters above ground |
| apparent_temperature | Instant | °C (°F) | Apparent temperature is the perceived feels-like temperature combining wind chill factor, relative humidity and solar radiation |
| cloudcover | Instant | % | Total cloud cover as an area fraction |
| windspeed_10m | Instant | km/h (mph, m/s, knots) | Wind speed at 10 meters above ground. Wind speed on 10 meters is the standard level.. |
| winddirection_10m | Instant | ° | Wind direction at 10 meters above ground. |
| windgusts_10m | Preceding hour max | km/h (mph, m/s, knots) | Gusts at 10 meters above ground as a maximum of the preceding hour |
| shortwave_radiation | Preceding hour mean | W/m² | Shortwave solar radiation as average of the preceding hour. This is equal to the total global horizontal irradiation |
| direct_radiation direct_normal_irradiance | Preceding hour mean | W/m² | Direct solar radiation as average of the preceding hour on the horizontal plane and the normal plane (perpendicular to the sun) |
| diffuse_radiation | Preceding hour mean | W/m² | Diffuse solar radiation as average of the preceding hour. MET Nordic does not offers diffuse and direct radiation directly. It is approximated based on Razo, Müller Witwer |
| vapor_pressure_deficit | Instant | kPa | Vapor Pressure Deificit (VPD) in kilopascal (kPa). For high VPD (>1.6), water transpiration of plants increases. For low VPD (<0.4), transpiration decreases |
| et0_fao_evapotranspiration | Preceding hour sum | mm (inch) | ET₀ Reference Evapotranspiration of a well watered grass field. Based on FAO-56 Penman-Monteith equations ET₀ is calculated from temperature, wind speed, humidity and solar radiation. Unlimited soil water is assumed. ET₀ is commonly used to estimate the required irrigation for plants. |
| 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, snowfall and gusts. As MET Nordic has barely no information about atmospheric stability, estimation about thunderstorms is not possible. |
| 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 MET Nordic directly, instead it is approximated based on total precipitation and temperature |
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. |
| 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. |
| current_weather | Object | Current weather conditions with the attributes: time, temperature, windspeed, winddirection and weathercode |
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"