It's not the temperature, be it high or low that ruins drums, but the rapid change in temperature and more specifically...humidity. Wood is hygroscopic which is a fancy word for huge $#@% sponge. Wood will absorb or release water until it is in equilibrium with the surrounding air. When this happens slowly, the cells within the wood will adjust, but when this happens quickly, it can lead to cracking and warping. One of the worst scenarios, is when you take damp wood, something that's been in a humid environment, and then immediately expose it to freezing temperatures. What happens here, is the frozen water trapped within the wood will expand and damage fibers before it has a chance to evaporate. Another bad one...is taking drums from the back of your cold, dry, Detroit-winter tour van, and immediately unloading under the 80F stage lights of that damp, stinky bar....and then 3 hours later back into the van. These are the situations people are thinking of when they say things like "let the drums warm up slowly before playing".
One thing you don't want to do, and this is important...constantly warming and cooling the drums every time you practice. If you can't maintain a constant temperature and humidity artificially, then it's best to leave the environmental regulating to mother nature. Extremely cold and dry drums or extremely hot and damp drums, that remain fairly constant and/or slow to change...are going to be FAR better off than drums that are going up and down quickly with every practice session.
