Yes sometimes the BS gets thick around here.Never had a lead/acid car battery last 15 years? You must live in an extreme climate.
95f day temps during the summer and winter temps below 32f really kill a battery.
Heat is the killer. Cold just shows you the weakness it isnt harmful to the battery.
Humidity doesnt affect the battery so even though 95 and swamp is miserable.. for a battery its purely the heat..
IE. Phoenix is among the worst climates in the US for a battery.