Preliminary data indicates that summer 2016 ranked as the 4th warmest summer season since records began in 1895. The statewide mean summer temperature of 76.6°F was 2.1°F above the 1981-2010 mean value of 74.5°F (Figure 1). Delaware’s four warmest summer seasons have all occurred since 2010.
The statewide mean precipitation of 12.4 inches was 0.40 inches above the 1981-2010 normal of 12.0 inches, and was the 4th year in a row with above normal summer precipitation (Figure 2).
Statewide Spatial Averages
Data from the Delaware Environmental Observing System (DEOS) show that summer temperatures were above normal across the majority of the State, with northern New Castle County and Chester County, PA having the largest positive anomalies (Figure 3). The Wilmington/New Castle County Airport recorded 34 days of temperatures greater than or equal to 90°F, twice the normal number. Only two years, 2010 and 1988, had more 90°F summer days than 2016.
Summer precipitation varied significantly across the State depending upon location (Figure 4). The variable pattern of precipitation is due to the small-scale nature of convective storms; dropping heavy precipitation in some areas, while leaving others relatively dry.