Preliminary data indicates that the statewide average temperature in December was 39.3°F, 1.2°F above the 1981-2010 normal of 38.1°F (Figure 1). December was the sixth month in a row with temperatures appreciably above normal across the First State. Even though Delaware experienced above normal temperatures during December 2016, it was still 11.5°F cooler than the extreme warmth experienced across the State during December 2015.
Delaware’s statewide precipitation for December 2016 averaged 3.11 inches, 0.46 inches below the 1981-2010 mean of 3.57 inches (Figure 2). December 2016 was the third month in a row with below normal precipitation.
Statewide Spatial Averages
Data from the Delaware Environmental Observing System (DEOS) shows that temperatures were uniformly above normal across northern Delaware and Chester County, PA during December (Figure 3). Temperature anomalies were generally small and varied between positive and negative values across the rest of the State. Precipitation was below normal at each DEOS station, with the largest negative anomalies found across northern New Castle County (Figure 4).