The extreme temperature danger to pets in the cargo hold is not so much when they are in the air, as it is before flight during storing, loading and taxiing.  You can find the NY Port Authority's airport regulations at, but no state, agency or airline can regulate temperatures inside a cargo hold on any given day at every takeoff and departure location, especially since unexpected delays on the ground have become fairly common.  

Each airline has their own policy for animal transportation in the hold.  Most airlines will not transport pets as cargo between mid-May and mid-September or when temperatures exceed 85 degrees F, and some airlines will not put pets in the cargo hold at all.  It's best to check with the individual airline(s) prior to booking any flights with an animal.  This link,, provides information regarding all of the different airlines’ policies regarding traveling with a pet.