WeatherWhys for May 23,2014 from accuweather.com

Across the northeastern corner of the U.S., a large storm system and/or cool, damp air flowing in from the ocean have a tendency to foul up the Memorial Day weekend weather. Daytime heating or a cool front may stir up thunderstorms on the Fourth of July, but the weather tends to be better on average. Of all the warm season holidays, the best weather typically occurs on Labor Day. At that time, widespread rains are unlikely and the convective season is just about over. One of the few weather spoilers that day would be a tropical storm or hurricane.