Saying goodbye to A.C. means saying hello to the world. With more people spending more time outdoors — particularly in the late afternoon and evening, when temperatures fall more quickly outside than they do inside — neighborhoods see a boom in spontaneous summertime socializing.

Rather than cowering alone in chilly home-entertainment rooms, neighbors get to know one another. Because there are more people outside, streets in high-crime areas become safer. As a result of all this, a strange thing happens: Deaths from heat decline. Elderly people no longer die alone inside sweltering apartments, too afraid to venture outside for help and too isolated to be noticed. Instead, people look out for one another during heat waves, checking in on their most vulnerable neighbors.

Children — and others — take to bikes and scooters, because of the cooling effect of air movement. Calls for more summer school and even year-round school cease. Our kids don’t need more time inside, everyone agrees; they need the shady playgrounds and water sprinklers that spring up in every neighborhood.