You're correct - I'm in Dallas weather such that we keep irrigation running all year. The killer is unintentionally running it when it freezing or below. Heads split, and the city issues fines if ice forms on sidewalks / streets.
I want to run my Iro 2 as 'set and forget' - it's supposed to be capable of this, and for the most part it does.
One area it doesn't is with freeze protection. You're not going to get it, when the Iro 2 is set for full auto ('Flex Daily), unless you have a weather station nearby, that you're comfortable you will always be connected to, that is accurate, and you're happy with the freeze threshold set at a fixed 32 degrees.
I'd prefer to see a couple of terminals put in a future Iro generation, dedicated just for freeze monitoring. No weather to find, no Internet connection required to be maintained, and no accuracy concerns of the weather station.
This may not ever happen. Rachio advertises itself as a software company where a hardware improvement may be longer to come by, and, I don't think Rachio has reservation of freeze protection being obtained via the Internet.
For absolute certainty that watering in freezing temps does not occur, local control is needed. Since I have a home automation system, where outside temp is one of many inputs, I'm going to put one of the automation system's relays in series with Iro 2's common wire out to the valves. And set the automation system to 'trip' the relay at 39 degrees.
Not a very elegant solution as I'll loose tracking of moisture levels in each zone. But I don't know of any other way than what I described above to ensure freezing temperatures are not missed by the Iro 2.