It’s not just therain. May has been an unusual month in New Jersey for another reason: We haven’t had any 80-degree days. We’re almost halfway through the month, and the temperature hasn’t hit 80 yet at any of the state’s three main weather reporting stations operated by the National Weather Service: Newark Liberty International Airport, Trenton Mercer Airport in Ewing and Atlantic City International Airport in Pomona. The trend is the same in 65 towns across the Garden State that have automated temperature gauges monitored by the Rutgers NJ Weather Network. As of early Thursday afternoon, non…