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 does not 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.