You don't ever leave the caps off a battery, (if that is what you were suggesting) no matter what the temps are. That is a myth started many moons ago, for who knows what reason. The vents in the caps are much more than adequate to handle any amount of amps the batts will ever receive.
And IMO,.....and many years experience, if you need to add water more than every 6 months, you need a new 3-4 stage converter charger, or a new solar controller.
That's not to dispute the suggestion to check levels every month if it suits you.