BOM Forecast API
Weather forecasts from the Australian Bureau of Meteorology
BOM is currently upgrading its key platforms and services. During this process, open-data
delivery has been temporarily suspended. We look forward to BOM resuming open-data access soon
so that high-resolution forecasts are once again available to Australian citizens.
This API provides weather forecasts based on the global ACCESS-G model from the Australian
Bureau of Meteorology (BOM). For more comprehensive applications, we recommend the Weather Forecast API, which utilises multiple local weather models for forecasts extending up to 16 days.
Data Sources
The API relies on weather forecasts generated by the ACCESS-G model from the Australian Bureau of Meteorology (BOM). It presents data in 1-hour intervals, delivering forecasts for a duration of up to 10 days. The model undergoes four daily runs at 0:00, 6:00, 12:00, and 18:00 UTC.
| Weather Model | Region | Spatial Resolution | Temporal Resolution | Forecast Length | Update frequency |
|---|---|---|---|---|---|
| ACCESS-G | 🌍 | 0.15° (~15 km) | Hourly | 10 days | Every 6 hours |
Native Model Variables
ACCESS-G directly predicts the fields listed below. Open-Meteo retains these fields or uses them to calculate more convenient API variables. ACCESS-G provides both global and direct solar radiation and native convective rain.
| Native ACCESS-G field | Level | Use in the Open-Meteo API |
|---|---|---|
| Temperature | 2 m, surface | temperature_2m, surface_temperature |
| Relative humidity | 2 m | Relative humidity and dew point |
| U and V wind components | 10 m, model levels near 40/80/120 m | Wind speed and direction |
| Wind gusts | 10 m | wind_gusts_10m |
| Mean sea-level pressure | Mean sea level | pressure_msl and derived surface pressure |
| Precipitation, convective rain and snow | Surface | precipitation, showers, snowfall |
| Global and direct solar radiation | Surface | Global, direct, diffuse radiation, DNI and GTI |
| Cloud cover total, low, mid and high | Surface | cloud_cover and the individual layers |
| Visibility and thunderstorm field | Surface | visibility and weather-code inputs |
| Soil temperature and moisture | 4 layers | Soil temperature and moisture variables |
Precipitation probability is calculated from the ACCESS-GE ensemble. BOM does not provide a native CAPE field.
Derived Variables
ACCESS-G publishes relative humidity, cloud cover layers, both global and direct solar radiation, showers, wind gusts and visibility natively. Open-Meteo derives the remaining API variables from these native fields.
| Derived Variable | How it is derived? |
|---|---|
| Weather code | Computed from cloud cover, precipitation, convective rain, snowfall, wind gusts, a native thunderstorm field and visibility. |
| Wind speed and direction | Calculated from the native U and V wind components at 10 m and from model levels near 40 m, 80 m and 120 m. |
| Precipitation probability | Share of the ACCESS-GE ensemble members with more than 0.1 mm/h of precipitation. |
| Snowfall and rain | Snowfall converts the native snowfall water equivalent with 0.7 cm per mm. Rain is total precipitation minus snowfall water equivalent and showers. |
| Diffuse radiation | Global minus native direct radiation. DNI, GTI and instant values follow from solar geometry. No radiation separation model is required. |
| 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. |
| Apparent temperature, ET₀ and sunshine duration | Combine temperature, humidity, wind speed and solar radiation. ET₀ follows the FAO-56 Penman-Monteith equation; sunshine duration counts time with DNI above 120 W/m². |
Sunrise, sunset, daylight duration and the day-or-night flag are astronomical calculations. Daily values are aggregated from hourly data.
API Documentation
The API endpoint /v1/bom accepts a geographical 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. If &forecast_days=16 is set, up to 10 days of forecast can be returned. All URL parameters are listed below:
| Parameter | Format | Required | Default | Description |
|---|---|---|---|---|
| latitude, longitude | Floating point | Yes | Geographical WGS84 coordinates of the location. Multiple coordinates can be comma separated. E.g. &latitude=52.52,48.85&longitude=13.41,2.35. To return data for multiple locations the JSON output changes to a list of structures. CSV and XLSX formats add a column location_id. | |
| 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. | |
| 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. | |
| temperature_unit | String | No | celsius | If fahrenheit is set, all temperature values are converted to Fahrenheit. |
| wind_speed_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 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. For multiple coordinates, a comma separated list of timezones can be specified. |
| past_days | Integer | No | 0 | If past_days is set, past weather data can be returned. |
| forecast_days | Integer (0-16) | No | 7 | Per default, only 7 days are returned. Up to 16 days of forecast are possible. |
| forecast_hours past_hours | Integer (>0) | No | Similar to forecast_days, the number of timesteps of hourly data can controlled. Instead of using the current day as a reference, the current hour is used. | |
| 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). | |
| start_hour end_hour | String (yyyy-mm-ddThh:mm) | No | The time interval to get weather data for hourly. Time must be specified as an ISO8601 date (e.g. 2022-06-30T12:00). | |
| 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 an average or sum.
| Variable | Valid time | Unit | Description |
|---|---|---|---|
| temperature_2m | Instant | °C (°F) | Air temperature at 2 meters above ground |
| relative_humidity_2m | Instant | % | Relative humidity at 2 meters above ground |
| dew_point_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 |
| pressure_msl surface_pressure | Instant | hPa | Atmospheric air pressure reduced to mean sea level (msl) or pressure at surface. Typically pressure on mean sea level is used in meteorology. Surface pressure gets lower with increasing elevation. |
| cloud_cover | Instant | % | Total cloud cover as an area fraction |
| cloud_cover_low | Instant | % | Low level clouds and fog up to 3 km altitude |
| cloud_cover_mid | Instant | % | Mid level clouds from 3 to 8 km altitude |
| cloud_cover_high | Instant | % | High level clouds from 8 km altitude |
| wind_speed_10m wind_speed_40m wind_speed_80m wind_speed_120m | Instant | km/h (mph, m/s, knots) | Wind speed at 10, 40, 80 or 120 meters above ground. Wind speed on 10 meters is the standard level. |
| wind_direction_10m wind_direction_40m wind_direction_80m wind_direction_120m | Instant | ° | Wind direction at 10, 40, 80 or 120 meters above ground |
| wind_gusts_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. |
| global_tilted_irradiance | Preceding hour mean | W/m² | Total radiation received on a tilted pane as average of the preceding hour. The calculation is assuming a fixed albedo of 20% and in isotropic sky. Please specify tilt and azimuth parameter. Tilt ranges from 0° to 90° and is typically around 45°. Azimuth should be close to 0° (0° south, -90° east, 90° west, ±180 north). If azimuth is set to "nan", the calculation assumes a vertical tracker (east-west). If tilt is set to "nan", it is assumed that the panel has a horizontal tracker (up-down). If both are set to "nan", a bi-axial tracker is assumed. |
| sunshine_duration | Preceding hour sum | Seconds | Number of seconds of sunshine of the preceding hour per hour calculated by direct normalized irradiance exceeding 120 W/m², following the WMO definition. |
| vapour_pressure_deficit | Instant | kPa | Vapor Pressure Deficit (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. |
| weather_code | 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, cape and gusts. |
| 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 |
| rain | Preceding hour sum | mm (inch) | Rain from large scale weather systems of the preceding hour in millimeter |
| showers | Preceding hour sum | mm (inch) | Showers from convective precipitation in millimeters from the preceding hour |
| snow_depth | Instant | meters | Snow depth on the ground |
| visibility | Instant | meters | Viewing distance in meters. Influenced by low clouds, humidity and aerosols. |
| soil_temperature_0_to_10cm soil_temperature_10_to_35cm soil_temperature_35_to_100cm soil_temperature_100_to_300cm | Instant | °C (°F) | Temperature in the soil as an average on 0-10, 10-35, 35-100 and 100-300 cm depths. |
| soil_moisture_0_to_10cm soil_moisture_10_to_35cm soil_moisture_35_to_100cm soil_moisture_100_to_300cm | Instant | m³/m³ | Average soil water content as volumetric mixing ratio at 0-10, 10-35, 35-100 and 100-300 cm depths. |
Daily Parameter Definition
Aggregations are a simple 24 hour aggregation from hourly values. The parameter &daily= accepts the following values:
| Variable | Unit | Description |
|---|---|---|
| temperature_2m_max temperature_2m_min | °C (°F) | Maximum and minimum daily air temperature at 2 meters above ground |
| apparent_temperature_max apparent_temperature_min | °C (°F) | Maximum and minimum daily apparent temperature |
| precipitation_sum | mm | Sum of daily precipitation (including rain, showers and snowfall) |
| snowfall_sum | cm | Sum of daily snowfall |
| precipitation_hours | hours | The number of hours with rain |
| sunrise sunset | iso8601 | Sun rise and set times |
| sunshine_duration | seconds | The number of seconds of sunshine per day is determined by calculating direct normalized irradiance exceeding 120 W/m², following the WMO definition. Sunshine duration will consistently be less than daylight duration due to dawn and dusk. |
| daylight_duration | seconds | Number of seconds of daylight per day |
| wind_speed_10m_max wind_gusts_10m_max | km/h (mph, m/s, knots) | Maximum wind speed and gusts on a day |
| wind_direction_10m_dominant | ° | Dominant wind direction |
| shortwave_radiation_sum | MJ/m² | The sum of solar radiation on a given day in Megajoules |
| et0_fao_evapotranspiration | mm | Daily sum of ET₀ Reference Evapotranspiration of a well watered grass field |
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", ...],
"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 kilometres away from the requested coordinate. |
| elevation | Floating point | The elevation from a 90 meter digital elevation model. This effects which grid-cell is selected (see parameter cell_selection). Statistical downscaling is used to adapt weather conditions for this elevation. This elevation can also be controlled with the query parameter elevation. If &elevation=nan is specified, all downscaling is disabled and the average grid-cell elevation is used. |
| 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"
}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 |
(*) Thunderstorm forecast with hail is only available in Central Europe