If you'd listened to a weather forecast on this date thirty-five years ago, you would have heard something pretty unusual for this time of the year: "freeze expected tonight." And in fact, the temperature on the morning of May 11, 1966, bottomed out at 32^o in Wilmington and a frosty 28^oF in Philadelphia. In the latter city, May 11 is still in the record books as the date of the latest freeze in spring and the only day in May when the temperature went below freezing.

Weather conditions that morning were ideal for producing a chill: clear skies, light winds, and high pressure right overhead. But there was another background factor that likely contributed to that unseasonably cold morning.

At that time, our region was in the throes of a long drought that, to this day, remains the most severe in history. A deficit of nearly 40 inches of rain had built up over the previous three years, and the ground and the air were very dry. And its that excessive dryness that aided in creating the chill. You see, the drier the ground and the air, the more efficiently they lose their heat at night. And so, in a way, the drought helped amplify what would have already been a chilly morning, turning it into a record-shattering one.