Yesterday was so hot and sticky the National Weather Service issued a heat advisory, which it does whenever the heat and humidity combine to make the temperature feel like 95 degrees or more. The high temperature was 92, and today's expected to get even grosser, with a high of 93 expected. Some combination of heat and mental illness may have driven 27-year-old Joshua Knee to dive into the East River at 72nd Street yesterday; Firefighter Justin McNally, who helped fish Knee out of the swift-moving soup, tells the Daily News, "I think he was just going for a swim." Knee was wearing swim trunks, and is now being held in the psychiatric ward at New York-Presbyterian Hospital Weill Cornell.

Firefighters also had to revive a roofer who collapsed, possibly from a heart-attack, while working in Corona, Queens. Tescuer Lt. Jim LoFaso of Engine 289 reports, "He was up on the roof and the sun was beating down pretty good. The shock restored his pulse, so we knew he had a chance." State officials are expected to issue another air quality advisory today because of heightened ozone levels, and anyone with a respiratory disease is urged to limit activity. On Wednesday the city should get a bit of a break, when clouds and thunderstorms are expected to roll in, bringing slightly cooler temperatures.

In the meantime, here is the city's index of air-conditioned cooling centers, and the official Office of Emergency Management warning about our "urban heat island." The Caring Community in Greenwich Village had the A.C. on full blast yesterday, which was appreciated by many local senior citizens—at least until they kicked everybody out. Jim Fouratt, 68, lamented, "I am dependent on places like this. But they close at 5 o'clock. The heat doesn't stop at 5 o'clock."And Brokelyn spent the day at the Dorchester Senior Center, located in the basement of an Orthodox synagogue. In that cool urban oasis, tuna sandwiches cost a dollar, there's Wi-Fi, and Wednesday is baked chicken day!