I've been using up some bulk 35 mm Tri-X that sat in my van, in direct sun, for several weeks in late summer almost two years ago (probably repeatedly reaching temperatures above 40C for several hours at a time). It's got a little fog, but it's very mild in a developer that contains an anti-foggant like HC-110 -- and given it's 5+ years expired, I don't know how much of that is due to the heat, and how much due to plain old age. Either way, the last of it is in cassettes now, and it's still quite usable...