I’ve been running OpenSprinkler in Laveen, AZ since 2013 (and before that in Tucson). I didn’t have any problems when I had by controller outside, but last year I moved it into the house and it has been great. I simply had to reroute valve wiring through the attic to my media panel. Its wonderful having everything centralized.
Now if only OpenPool would come out to take over control of my pool equipment!;)