I'm not sure if you're still interested in a detailed answer, but I'll post it nonetheless:
1) If the water is warm, then I will take a shower.
(Nothing is said about any other temperature though (cool, cold, freezing etc), so we do not specify if we are going to take a shower at any other condition (temperature), but we explicitly note that if it's exactly WARM, then we will DEFINITELY take a shower.)
2) If the water is anything BUT cold (i.e. it is warm, cool, freezing etc) I will DEFINITELY take a shower. The only condition that I don't take a shower is if the water is EXACTLY cold.
(Note that "not cold" does NOT necessarily equal warm. As I've already specified above it can be warm, cool, freezing to name a few.)
3) If the water is warm I may or may not take a shower, BUT If you see me taking a shower, then you can be sure the water is warm, because I was only going to take it if the water was warm.