I'm local and yesterday got really hot before it got more cloudy,in the middle of the day with the temps around 90 and heat indexes close to 100 I saw a guy running in a long sleeve zipper pullover while I'm sweating wearing a thin t shirt inside a car with ac.I dont even wear those to run when its 60 degrees,it needs to be like 45 for me to even consider wearing one of those in a run outside but your comment made me think that the guy must be trying to lose weight by sweating.I will say Orlando once the sun goes down does cool off more than my old area in Miami,down there its not uncommon for a summer night to only drop to 84 degrees,in Orlando youre at least going to be in the 70's,but still unless you go in a cold building you dont need a sweater.Not unless you're trying to do one of those "sweat it out" diets.
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I couldn't imagine wearing anything more than a t shirt outside of Dec-Feb.
One year, I went at the end of June. I came home NINE pounds lighter, due to the humidity. The best diet I"ve ever been on!