Because temperature extremes cause batteries to deteriorate much faster, it is important that you keep your batteries in a place where the temperature is relatively stable.
Aside from enclosed above-ground structures, you can also create a structure that is partially underground. This way the temperature in the structure will remain the same no matter what the weather is like outside.
In addition, make sure that the charge controller or inverter system has a built in temperature compensation feature. This is necessary because the charge voltage limit of a battery increases as temperature drops and decreases at temperatures increase.