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Availability and staleness

A sensor can be without a current value for two different reasons, and they show differently:

StateCauseWhat to do
unavailableThe integration has no current file for the product: DWD is late, or Open Data cannot be reachedNothing; it recovers on the next successful fetch
unknownThe file is there, but holds no value for your location (a radar outage), or there is nothing to report (no rain forecast for Precipitation start)Nothing for an outage; it recovers with the next file that has data

When a value goes out of date​

While DWD is late, the last value is kept for a while: a file that arrives a few minutes late should not blank your dashboard. A product's sensors turn unavailable once the file that should have replaced their value is more than 6 minutes overdue (30 minutes for Precipitation yesterday).

The clock starts when the next file should have been on Open Data, not when the current value was published. For RS, with the release of 14:00 shown:

  • the release of 14:05 is due at about 14:09,
  • if it has not arrived by about 14:15, the RS sensors turn unavailable,
  • they come back as soon as any newer release is fetched.

The grace is the same for hourly and daily products, because it measures how long DWD is given to publish, not how old a value may be. Retries continue throughout, see Release timing.

Keeping the last value instead​

With the advanced option Show "unavailable" when the data is out of date turned off, sensors always keep their most recent value, however old. That suits dashboards that should never show a gap, but the value can then be hours old without any sign of it. The technical details attributes (source_timestamp) tell you how old it is.

Exceptions​

No data for your location​

A radar dropping out of DWD's composite leaves the cells only it covered without data, while every file still downloads fine. The sensors of that product are then unknown. The log gets one warning when data goes, naming the radar(s) missing when it can tell, and one message when it is back, and nothing in between.

If that warning appears right after setup and data never arrives, the location is outside the area that product covers; see Grid cell lookup.

One product at a time​

Each DWD product is fetched on its own schedule, and its failures affect only its own sensors. If DWD stops publishing one product, its sensors become unavailable while all others keep working, and the log says which one failed. The integration only fails to start if every product fails, for example when there is no internet connection; Home Assistant then retries the setup on its own.