I dont use the integration that you are using but normally a weather integration should provide you a weather entity. Just simply look up in the integration page which entities the integration created.
This weather.(somebytheintegrationprovidedname) entity normally shows you a state which is the actual weather condition like “sunny” “cloudy” “rainy” or whatever. This condition is what you can use as the trigger for your automation
It depends a bit on the sensor you use.
If you use weather.buienradar, your trigger could/should be something like this:
trigger:
- platform: state
entity_id:
- weather.buienradar
to: rainy
If you use the Condition detailed, Buienradar - Home Assistant, you likely need to add some more states. If I am not mistaking, you can add the states like this, using yaml mode:
platform: state
entity_id:
- sensor.buienradar_detailed_condition
to:
- rainy
- partlycloudy-rain
- light-rain
- snowy-rainy
- partlycloudy-light-rain
- etc
You don’t necessarily need to enter the from-state.
In the action you need to put the action to close your rollershutter. I cannot help you with that without you sharing your automation.