Talk about hot nights, America got some for the history books last month. The continental United States in July set a record for overnight warmth, providing little relief from the day’s sizzling heat for people, animals, plants and the electric grid, meteorologists said. The average low temperature for the Lower 48 states in July was 63.6 degrees (17.6 Celsius), which beat the previous record set in 2011 by a few hundredths of a degree.