The residence halls at Mount Holyoke are wonderful indeed but as far as I know only one, the recently-constructed Creighton Hall, is air-conditioned. You might want to contact the College if you apply and get in to make sure that the appropriate authorities are aware of your need for air-conditioning. I suspect that might land you a coveted spot in Creghton Hall. Most students would prefer the other dorms that are more historic with bigger rooms or those that have picture windows over looking the lakes and lots more character. Fortunately, at Mount Holyoke, you get a chance to move every year and can get an equal opportunity to land a room in your favorite dorm.