The cold weather just helps kill a dying battery but wont affect a good battery, period. Thats why the battery has cranking amps and cold cranking amps listed on it. And Optimas totally SUCK ASS!!!! My Wal Mart Ever Start battery has never failed and I have had three optimas.....pure shit, my brother has had 4 replaced in his truck under warranty, what a waste of time, he went back to an interstate, also an excellent battery. Just avoid Optimas and les schwabs batterys.