@bjarnej
In aviation weather apps, they show the temperature at the airport/ aerodrome where there is generally a weather station. They cannot compute real temperature with any weather model.
In Windy you can check the reported temperature at Karstrup airport. It is true that Meteoblue provide a more accurate temp than GFS, ECMWF and even ICON D2.

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Click Reported temperature to get the Observation vs forecast feature and last reported temp at this weather station.