I have never heard this before.
In my experience, hair products are fairly stable when it comes to changing temperatures. If they are in sealed airtight containers, I can't see how humidity would be a factor either.
Although it may be possible for temperature to be a factor, I have never found that to be the case. I have kept some hair products (cremes, pastes, gums, and putties) for years without noticing any change in their constitution.