Hi @radamio, good evening.
A rain sensor has it's pros and cons:
1. It's on site -- no microclimate concerns
2. Cheap and easy to install
1. Only reactive, not proactive (i.e., a rain sensor will only interrupt the common wire once it's wet -- it will not skip a watering schedule based on future rain)
2. Limited functionally -- it can only interrupt the common wire.
All things equal, if in doubt (or concern), a rain sensor is a cheap insurance policy if you want to make sure the Iro never waters in the rain. While we'll be adding CA restriction rules to the app, this rain sensor can be programmed to interrupt the common for up to 72 hours anytime it gets wet (it's also super easy to install). Combine that with the predictive skip functionally of the Iro and you'll always be in compliance.
Hope this helps