I am from the VERY deep south and our temps have recently been in the upper 90's, and soon to be 100+. I run a 4x2x5 tent with a 250hps cool tube, the room the tent is in keeps an ambient of 77 to 79, the tent during lights on is 80 to 87. I run a 170cfm fan w/carbon filter that is ducted into the ceiling. Inside the tent I have one 9" floor fan, and two 6" clip on fans above the canopy that keeps the air moving nicely. I was using my 400w dual arc but temps went to 94, so just swapped out for my 250hps. I have a local friend that has been growing for years, and his temps run 88 to 95 with no noticable issues for him, and he has some of the best smoke. I was originally worried about my temps, but once I seen his temps I stopped stressing.