I did not know this. I always thought that if the film were allowed to get warm, that the colors would shift and bad things could happen LOL. I guess that makes sense though; film stays warm the entire time it is in the camera body, which in my case can be weeks/months sometimes.
At 25C, several months mean nothing.
At 5C, a year or two means nothing.
At -18C, several years mean nothing.
And with "nothing", I mean absolutely nothing. Usually film that has been a year or two in room temp is completely usable, though, with very little effects.
You can extrapolate a little. At car window it can reach 50C and it may survive this shock but will deteriorate quite quickly, if you keep it there for days (or weeks).
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Except for Pro emulsions, no need to fridge it, as long as it is kept cool and free from extreme high temp. I keep film in the fridge as much because it means I know where it is as for any other reason.
Some stuff I really want to keep well past expiration date is in a freezer in the basement, though; along with Boesplug, et Cie Zone VI Brilliant, original Seagull, and maybe some Agfa Record Rapid. I guess I should do an inventory.
I keep my film in the freezer because I have some discontinued emulsions. And I have the space for the film. Freezing keeps it as fresh as I possibly can. [Especially the HIE]