As long as your garage temp is less than 40 C, (104° F), you won't damage the motor insulation...
HEAT is death to most electrical devices, not lack of heat.
Batteries should always be stored fully charged, on a trickle charger, in a clean, dry environment at a temperature above freezing and no higher than what is comfortable for a human being.
The key to getting all of the engineered life from a device is to make sure you NEVER exceed the insulation temperature rating... cold storage is fine.