In central NC we get plenty of humid days in the 90s (some over 100). My commute is 10 miles. I start drinking water maybe an hour or two before I ride home. I wear a wet coolmax dew rag under my helmet and I don't push my self too hard on the ride home. On really hot days I carry 2 water bottles, one to drink and one for squirting on the front of my jersey to keep me cool. I am going to start wearing sunscreen on the ride home.