When I was living in Southern California, I left an unexposed roll of Koda Ektar in my car for two months in the glove compartment over the summer. Temps where I lived in Valencia, CA reached 95+ for month straight that year. I did not notice anything wrong with the final developed film when I got around to it in the fall.
This has been my experience too. I usually keep a camera loaded with Tri-X in the glove box; sometimes it takes months to finish the roll, and in inland Southern California that car can get *seriously* hot. I've never been able to detect anything wrong with the film after developing---I suppose there might be some degradation, but it's below what's obvious to my eye.
Color film is reputedly more sensitive than b&w, but the quote above would suggest that even with color there are likely no grounds for panic.
San Diego, CA, USA
The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
-The Little Technical Library, _Developing, Printing, And Enlarging_
Having shot most of my film in SE Utah during summer and winter months I have learned two things in regard to film and temperatures:
1) Anything above 110F for multiple days can shift colors slightly (never had issues with BW though). I've taken a thermometer reading of the temp 6" above the hot sand/sandstone in Utah and got up to 145F, so I no longer leave my film near the ground on the hottest of days.
2) Anything below -15F can also color shift. Same area of the country, but after hiking for 3 days with mostly Velvia 50 with lows near -20 I've learned that the film gets purpleish. Also, first time I've ever had a shutter stick from cold--had to hit it with my hand pretty hard to get it to snap back shut.
Moral of the story is, unless it's fairly extreme temperatures for prolonged periods of time, not sure if I'd worry.