UK Met Office API
Weather forecasts from the United Kingdom's national weather and climate service UKMO
Data Sources
This API uses global UKMO Global 10 km weather forecasts and combines them with high-resolution UKV 2 km model for the United Kingdom and Ireland. Information about UKMO weather models is available here. For UKMO Global, values are interpolated from 3-hourly to 1-hourly after 54 hours and from 6-hourly data after 144 hours.
Note: UKMO open-data has an additional delay of 4 hours. The forecast is therefore not as accurate as it could be.
| Weather Model | Region | Spatial Resolution | Temporal Resolution | Forecast Length | Update frequency |
|---|---|---|---|---|---|
| UKMO Global | 🌍 | 0.09° (~10 km) | Hourly, 3-hourly after 54 hours, 6-hourly after 144 hours | 7 days | Every 6 hours |
| UKMO UKV |   | 2 km | Hourly | 2 days | Every hour |
Native Model Variables
The UK Met Office directly predicts the fields listed below. Open-Meteo retains these fields or uses them to calculate more convenient API variables. Unusually, UKMO provides wind as speed and direction, and relative humidity and direct radiation natively.
| Native UKMO field | Level | Use in the Open-Meteo API |
|---|---|---|
| Temperature | 2 m, height levels (UKV), pressure levels | temperature_2m and upper-level temperature |
| Relative humidity | 2 m, pressure levels | Relative humidity, dew point and pressure-level cloud cover |
| Wind speed and direction | 10 m, height levels (UKV), pressure levels | wind_speed_10m, wind_direction_10m |
| Wind gusts | 10 m | wind_gusts_10m |
| Mean sea-level pressure | Mean sea level | pressure_msl and derived surface pressure |
| Precipitation, rain, snowfall, hail (UKV) | Surface | precipitation, rain, snowfall, hail |
| Shortwave and direct solar radiation | Surface | Global, direct, diffuse radiation, DNI and GTI |
| Cloud cover total, low, mid, high and fog fraction | Surface | cloud_cover, layers and cloud_cover_2m |
| CAPE, convective inhibition, visibility, UV index (UKV) | Surface | Corresponding API variables and weather-code inputs |
| Geopotential and vertical velocity | Pressure levels | geopotential_height, vertical_velocity |
Height-level variables, hail, freezing level and UV index are only available in the UKV 2 km model. Convective inhibition and pressure-level vertical velocity are only in the Global 10 km model.
Derived Variables
UKMO publishes unusually complete fields: wind is provided directly as speed and direction (no U/V components), relative humidity and direct solar radiation are native, and the UKV model adds rain, snowfall and hail as separate fields. The remaining API variables are derived by Open-Meteo.
| Derived Variable | How it is derived? |
|---|---|
| Weather code | Computed from cloud cover, precipitation, snowfall, wind gusts, CAPE, convective inhibition and visibility. UKMO's own significant-weather symbol is not used. |
| Snowfall and rain | On UKV, snowfall water equivalent and rain are native. On the Global 10 km model, precipitation is counted as snow below 0°C and rain is the remainder. Snowfall uses 0.7 cm per mm of water. |
| Solar radiation averaging | UKMO publishes instantaneous radiation fluxes. Open-Meteo converts them to hourly backwards-averaged values during download. Diffuse radiation is the difference of global and native direct radiation; DNI, GTI and instant values follow from solar geometry. |
| Dew point, vapour pressure deficit and wet bulb temperature | Calculated from native 2 m temperature and relative humidity. |
| Surface pressure | Calculated from mean sea-level pressure, 2 m temperature and terrain elevation. |
| Sunshine duration | Seconds per hour with direct normal irradiance above the WMO threshold of 120 W/m². |
| Apparent temperature and reference evapotranspiration ET₀ | Combine temperature, humidity, wind speed and solar radiation. ET₀ follows the FAO-56 Penman-Monteith equation. |
| Pressure-level cloud cover | Estimated from native pressure-level relative humidity. |
| Freezing level height (UKV) | Native field converted from height above ground to height above sea level using the model orography. |
Sunrise, sunset, daylight duration and the day-or-night flag are astronomical calculations. Daily values are aggregated from hourly data.
API Documentation
For a detailed list of all available weather variables please refer to the general Weather Forecast API. Only notable remarks are listed below
- Solar radiation:UKMO supplies shortwave radiation as instantaneous values. Open-Meteo transforms these into backward-averaged radiation to align with the definition used by other weather models. However, in the global domain, data shifts to 6-hour intervals, rendering instantaneous values useless at that temporal resolution. As a result, solar radiation forecasts are only offered for a 2-day forecast horizon, where 1-hourly data remains available.
- Direct Solar Radiation: UKMO provides direct solar radiation. Many other weather models only provide global solar radiation and direct solar radiation must be calculated user separation models.
- Wind, temperature and cloud forecasts on height levels 100m and above: Forecasts at different levels above ground are only available for the 2 km UKV model.
- Cloud Cover (2m): UKMO UKV 2 km provides cloud cover at 2 metre above ground which can be interpreted as fog. This is remarkable, because only very weather models are capable of modeling low level cloud cover and fog with a good degree of accuracy.