Temperature, air circulation, humidity all play a part (along with the recipe).
I haven’t found the heat to be a problem, but the cold and the damp is. Kind of. Sort of. Example, I made three soaps last weekend; Regular Soap, Coconut Soap, Salt Soap. My Regular Soap wan’t gelling when the temps dropped below 60F and it was taking a couple of days to unmold and then another couple of day to cut. So increased my lye concentration to 35% at someone’s suggestion and it helped, but still no gel. Then someone else suggest ‘oven process’ and that was helping, except this last time, I left the oven on and I noticed the top looked like the texture of an orange...not a biggies, I was just making soap for hubby and it’ll plane off. This was a 2lb loaf mold.
The Coconut and Salt Soaps where just 1lb batches in cavity molds. First time making a 100% Coconut Oil and I did an ITP (in the pot) swirl with some Rose Clay, no scent. Poured it, put it in the garage, unmolded two days later with no issue. Trimmed them today and they still looking good. Same with the Salt...poured it, put it in the garage and unmolded two days later and man they sure are purty! This is my third attempt at a Salt Soap and I am tickled pink so far. Went to check on tem today since I need to move them to the top shelf and I noticed they were weeping. Neither of my other attempts did this, but this is also a different recipe. Research says that this is not uncommon as salt will pull moisture from the air. And we had a lot of rain this last week. So after I planed them, I wrapped them in paper towels and put them on the top shelf.
Bottom line...hot and dry is good for soap, moisture will evaporate quicker. Cold and damp...not so much. But except for the time factor, it doesn’t seem to be harming any of the other soaps I have been curing.