DWD nowcast is a Home Assistant custom integration that provides a minute-by-minute precipitation nowcast for a configured location based on Deutscher Wetterdienst (DWD) Open Data.
Follow this link for the license terms of the DWD: https://opendata.dwd.de/README.txt
Forecasts are model-based predictions that try to predict the weather over the next days. They use large- scale weather models and calculate larger trends such as temperature changes, weahter fronts, and development of storms.
Nowcasts focus on the next upcoming minutes (upo to an hour in the case of this integration) and are based on radar images showing the position (and movement over multiple images) of precipitation cells. This makes them more accurate for short-term rain prediction.
If you want to know it will start to rain close to NOW, nowcasts are more reliable.
- Provides a 60-minute precipitation nowcast as a Home Assistant service
- Source: DWD Open Data radar nowcast (Radarkomposit RV)
- DWD Update interval: every 5 minutes
- Time resolution: 5 minutes, internally interpolated to per minute values by the integration
- DWD Forecast resolution: approximately 1 km grid
- Location mapping: Configured latitude/longitude is mapped to the nearest grid cell
This integration focuses on minute-by-minute precipitation ONLY. It does not expose standard weather conditions, temperature, or long-term forecasts. For full weather data from DWD, use this dedicated DWD weather integration: https://github.com/FL550/dwd_weather
Click this button
or
- In HACS, go to Integrations.
- Open the menu (top right) and choose Custom repositories.
- Add this repository URL and select Integration as category.
- Install DWD nowcast.
- Restart Home Assistant.
- Add the integration via Settings > Devices & Services.
- Copy the
custom_components/dwd_nowcastdirectory into your Home Assistantcustom_componentsdirectory. - Restart Home Assistant.
- Add the DWD nowcast integration in Settings > Devices & Services.
The integration registers a get_minute_forecast service for its weather entity:
action:
- service: dwd_nowcast.get_minute_forecast
target:
entity_id: weather.dwd_nowcast
response_variable: minute_forecastBesides the top level key with the service signature,
the service response is compatible with the OpenWeatherMap's get_minute_forecast format:
weather.dwd_nowcast:
forecast:
- datetime: "2026-01-26T19:10:00+00:00"
precipitation: 0
- datetime: "2026-01-26T19:11:00+00:00"
precipitation: 0
- datetime: "2026-01-26T19:12:00+00:00"
precipitation: 0
...In addition to the weather entity and its service, this integration creates three sensor entities per configured location. All sensor entities operate on a 60-minute window starting from the current time, matching the service output.
Returns the highest precipitation intensity (mm/h) found in the next 60 minutes. Useful as a quick indicator of how heavy upcoming precipitation will be.
The forecast attribute contains the next 60 minutes as a list of
{datetime, precipitation} objects:
forecast:
- datetime: "2026-01-26T19:10:00+00:00"
precipitation: 0.0
- datetime: "2026-01-26T19:11:00+00:00"
precipitation: 1.2
...Returns the precipitation intensity (mm/h) at the current minute. Useful for dashboards, history graphs, and intensity-based automation conditions such as alerting only when precipitation exceeds a certain strength.
Returns unavailable when no data is available for the current time (e.g. right after
startup before the first successful fetch).
Timestamp of the next minute where precipitation is expected to reach or exceed
the configured threshold (default: 0.1 mm/h). Searches forward from the current
time within the 60-minute window, so the value is always a future timestamp or
unavailable.
If precipitation is currently active, the sensor skips over the current event and
returns the onset time of the next precipitation event after the current one
ends. Returns unavailable when no precipitation is forecast within the window.
Timestamp of the minute when the current precipitation event is expected to drop below the configured threshold. Searches forward from the current time within the 60-minute window.
Returns unavailable when precipitation is not currently active, no data is
available, or precipitation persists through the entire 60-minute window without
dropping below the threshold.
on when the current minute's precipitation intensity meets or exceeds the
configured threshold. Returns unavailable when no data is available for the
current time (e.g. right after startup before the first successful fetch).
After adding the integration, a Configure button appears in Settings → Devices & Services → DWD nowcast. This allows changing:
| Option | Default | Description |
|---|---|---|
| Precipitation threshold (mm/h) | 0.1 | Minimum intensity to count as active or upcoming precipitation. |
Changes take effect on the next data refresh (within 5 minutes). No restart required.
Close windows as soon as precipitation starts:
automation:
- alias: "Close windows when precipitation starts"
trigger:
- platform: state
entity_id: binary_sensor.dwd_nowcast_precipitation_active
to: "on"
action:
- service: cover.close_cover
target:
entity_id: cover.living_room_windowNotify before precipitation is about to start (within 10 minutes):
automation:
- alias: "Notify before precipitation starts"
trigger:
- platform: state
entity_id: sensor.dwd_nowcast_next_precipitation
condition:
- condition: template
value_template: >
{{ states('sensor.dwd_nowcast_next_precipitation') not in ['unknown', 'unavailable']
and (as_timestamp(states('sensor.dwd_nowcast_next_precipitation')) - as_timestamp(now())) < 600 }}
action:
- service: notify.mobile_app
data:
message: "Precipitation expected in less than 10 minutes."Attention: The returned precipitation values are converted to mm/h as strength of rain. This has been done to be compatible to the OpenWeatherMap integration / action. The DWD itself returns mm values for ammount of rain in the given time period.
- DWD nowcast data is updated every 5 minutes and typically appears a few minutes after the timestamp in the filename.
- DWD RV values represent 5-minute accumulations in mm and are converted to mm/h to match the OpenWeatherMap-compatible response format.
- If the location is outside the DWD RV grid, the forecast list is empty.
- Radar nowcasts can be inaccurate for very small or fast-changing precipitation.