How to proof croissants in the hot weather?
30C is a good temp for proofing. Proofing overnight in fridge allows for greater flavour development in breads (or any yeasted dough), but they still need to be proofed further at room temp before bake. Croissants I have never seen proofed in the fridge - not saying it can't be done, but I've never seen it. The only time you should be truly concerned about a hot kitchen (in my opinion) is when you're working with chocolate. Because breads and yeasted things rise best between 27C and 38C with the optimum temperature being 35C. Check out this link for more info http://www.theartisan.net/dough_fermentation_and_temperature.htm

Good Luck! Croissants are a labour, but a delicious one!