High temps seem to be bad for pretty much all types of batteries, though cold temps tend to put a greater load on them, since engines are harder to turn over, and more 'stuff' is being run.
Interestingly, it doesn't seem to me like BMW batteries mounted in the trunk/under rear seat last much longer than Japanese/US ones mounted in the engine compartment. Considering how crappy the euro (mostly Varta) alkalines and lithiums I've used for non-car stuff, maybe euro batts just suck.
2001 325i Touring Alpinweiss/Anthracite cloth, Alpina Softline
1988 M6 Royalblau/Silbergrau Nappa