CONTRARY to popular belief, the first July Fourth, as experienced by the founding fathers, was not terribly hot. The temperatures in Philadelphia in July of 1776 never rose above 82 degrees Fahrenheit, as can be seen from this log kept by Thomas Jefferson. And on July 4th, the high was a mere 76 degrees.
However, the delegates of the Continental Congress were wearing wigs and frock coats, not T-shirts, baseball caps and fanny packs. There was no air-conditioning or electric fans, and a summer in Philadelphia was tropical compared to those in England. The average high in London in July is 72 (as compared to 86 in Philadelphia), and would have been lower in 1776, which was toward the end of the Little Ice Age. Therefore they are still deserving of admiration for their endurance.