Mine were up to around 95F when my lights were on, even with an A/C. Plants grew decent up until about week 6 of flower, then they started to droop. I'm partially attributing the drooping to the weight of the buds but I know the heat had a little to do with it too. It's do-able but you have to keep an eye on things just in case they show signs of heat stress. I know there's a range that they usually thrive best in so if there's a way to get temps down in your garage, I would advise it. Otherwise, the way I see it is that most places in the summer get up to between 90-110F. I've heard of a lot of people who grow outside in the hotter temperature and have a lot of success. You will have to pay pretty close attention to your watering but I feel like it can be done. A few fans and maybe a dehumidifier for flowering so you don't get bud rot. It's just a theory of mine so take it how you will, but I think with the right air circulation and watering practices you should be fine for the most part.