(1) The weather report says that it's going to hit 80 today. I do not deny it, but it is not 80 when I walk to work in the morning (especially early in the morning), and it's not 80 when I walk home--preferably as the sun sets enough to resemble a cool evening.
(2) I've survived 7 years in Miami and 2 weeks in Japan during the hottest and most humid month of the year. hammercock can verify the discomfort we faced as our old wardrobe (cotton T-shirt and blue jeans) didn't cut it and were quickly replaced by local wear. The weather in Boston right now does not compare.
(3) Frankly, I do look cool and feel in a leather trenchcoat. Sometimes, attitude helps.