What I see here is the use of el cleapo wire terminals failing that are corroded by sulfuric acid or by arcing from loose connections. I always replace them with cable lug terminals but that requires a hydraulic crimper. Now there is other half way crimpers out there; although, make lousy crimps.
Batteries do like in either cold or hot weather but they can fail at anytime. Case in point is where you crank up your vehicle in the morning, drive 25 miles to Tramlaw, Shut it down, then realize you parked on the wrong side of the parking lot. Then when you go start your engine nothing but a click. After getting a jump off and $200 later at the Auto Zone you're back in business. This one actually happen to me back in the Fall when I had replace my glasses due some big footed idiot crushed them. Guess who was the big footed idiot?
It was the third time this type of battery failure has happen to me. No warning signs.