Something to consider:
This is for those of us who have rain sensors connected to the Iro and enabled. If the weather service (or selected PWS located more than 1/4 mile away from Iro) reports precipitation sufficient to prevent the Iro from running BUT the rain sensor has not been activated in the same period, then assume negligible precipitation has actually occurred on the property and run / schedule watering as if no rain has occurred.
My goal with this is to avoid skipping watering in the case where it has rained buckets all around me, but my house has actually gotten little or no rain. This happens somewhat frequently where I am, especially in the summer. With my cool season grass in a hot summer climate, failing to water when needed can lead quickly to dead -- not just browning or wilted, but completely dead -- grass.
P.S. Note that I'm not saying that the rain sensor must remain activated, but just that it would have been activated at some point in, say the past 24 hours, for a precipitation report to be credible.