Rain gauge is currently not supported: at least not supported if you want to use it to stop watering when a certain amount of rain is received. Technically rain gauge works like a flow sensor — the reed switch internally turns on and off repeatedly to indicate the rate at which rain is accumulated. You can use rain gauge in the sense that you treat it like a flow sensor and you can check its reading. But you can’t use it to automatically trigger the stop of watering because such functionality is not implemented.