I do the same thing with my heat pump for when it gets excessively cold to prevent it from going into night and/or away mode. In my case, I prefer to have it keep the temperature steady instead of setting it back so that I do not have to run in AUX mode to get back to temperature.
I use the driver here: OpenWeatherMap-Alerts-Weather-Driver
NOTE: Per some of the more recent posts, if you do not have an old API key, you will have to sign up for the new one. This requires allowing a credit card to be stored on file in case you go over the polling limit (Not by the author of the app. The company providing the weather service requires this). You can poll every two minutes and still not exceed the limit for free usage though.
The rule looks like this:
