If you go into the Rachio app and under DEVICE SETTINGS, Standby mode is the 1st option. Turn this ON.
Also, go down the main page in the app and under EDIT WATERING SCHEDULE, click the schedule or schedules (if you have more than 1) and switch the ENABLED option OFF.
Then in the spring when you're gearing your system back up, turn the ENABLED back ON for each of your schedules and take the system Standby Mode OFF enabled.
BTW, I too am in Colorado so howdy from one Rocky Mtn'er to another.