Couple things. A dead battery will actually _freeze_ in cold weather, they are junk at this point, whereas a fully charged battery is good to go till -50° below zero (or some ungodly temperature.) Further, attempting to recharge a frozen battery may cause an explosion. Batteries are nothing to fool with!
As far as temperatures go though, in general cold temperatures for _storage_ are preferable, because, a lead-acid battery is basically nothing more than a self-contained chemical reaction. Like most chemical reactions, the higher the temperature, the faster the reaction, in this case natural rate of self-discharge, and then the negative plates start to sulfate very quickly.
It is hot weather or high temperatures that actually ruins a battery before their time, it just doesn't usually become apparent until cold weather arrives, when current demands are much higher and the battery ampere capacity is inhibited by the cold. This is why there is a "run" on car batteries every year at the auto parts houses once that first subzero cold snap hits.
Given a choice it's better bringing a battery in out of the heat and keep it in the basement as far as long term storage condition is concerned. I agree with the "charger on a timer" method being a better method versus a tender as such. The tenders do work though, just not as well.
If keeping a battery outside in the winter or somewhere it freezes make sure it is thoroughly charged before putting it away. A little attention towards battery needs will go a long way tohelp extend their service life, they are getting spendy.
