It really depends on the miner that you are using. If you for instance install the standard version of Nicehash miner they have an option which disables AMD driver heat control. Bad idea in a warm setting. For most other miners like Claymore you can use settings to tweak the blowers on the cards. Once that is done you need to watch that they are not too close together if it is a rig or that there is enough blowers when it is a fixed pc with just one card in it. Never ever use a multi GPU fixed closed pc, they will blow up the top GPU, allways. Have fun out there and good luck with your future posts!
RE: Mining in hot temperatures - Hardware failures / Decreased Hashrates? Tell your story.