Though the weather had cooled somewhat on Wednesday, Daryl Hadden did a brisk business in water bottles at the corner of 6th and Market Streets on Wednesday, July 27, 2016. Photo: Tom Avril, Philly.comThe nights are getting hotter in Philadelphia, and it has nothing to do with nightlife. Overnight temperatures have been creeping upward for the last 25 years, more robustly than daytime highs, and health experts say that is a cause for concern. An analysis of daily minimum temperatures showed that between 1