While the controller is outdoor-grade equipment, ControlOMatic states in their manual that you would want to bring the controller in once temperatures get below 32F. The controller is very easy to mount, so it should be pretty simple to bring it in if needed.
Here is a copy of the manual for more details:
https://www.discountsaltpool.com/assets/doc/Controlomatic-Chlormaker-Owners_Manual.pdf