May 2015 was a warm and dry month across New Jersey. As the month ended, drought concerns were looming large, though rainfall in the north during the afternoon and evening of the 31st and continuing into the first days of June resulted in at least a temporary braking of the downward slide. Based on data gathered at long-term National Weather Service Cooperative Observing (COOP) stations, May rainfall averaged 1.08" across NJ. This is 2.92" below the 1981-2010 mean and ranks as the 3rd driest May since records commenced in 1895.
As those who have been reading these monthly narratives for some time now know, precipitation that falls at COOP stations after observation time on the last day of the month gets recorded as falling on the first day of the next month. Most COOP stations observe in the morning, thus the heavy showers that fell across north Jersey on the 31st were not factored into this May average, except for a few stations such as Newark Airport (which registered 3.83" on the 31st alone) that observe at midnight. The last time this situation had a notable impact on monthly rainfall was a daytime heavy rain event on April 30, 2014.