I wanted to notify you of possible light overnight freezing in the near future. I have attached a diagram on draining your irrigation system as well as an instructional video from YouTube. This is similar to irrigation system winterization.
I am mainly concerned when overnight temperatures will be dipping below 30 degrees for an extended period of time. Soil temperatures are still between 60-65 degrees and it will take a long period of colder weather before those temperatures drop drastically.
With that being said, it is not likely that a few nights of cool temperatures would cause any damage to underground pipes. The main concern right now is the exposed pipes around your backflow preventer. Simply draining your irrigation should suffice for a weekend of cold temperatures. This will allow you to continue watering next week once low temperatures are back above freezing.
YouTube VIDEO SHOWING HOW TO DRAIN YOUR IRRIGATION SYSTEM
Let us know if you have any questions.