December 2023 – Very Warm with Record Precipitation

December Temperatures

Preliminary data indicates that the statewide average temperature in December was 44.0^°F, which is 4.5^°F above the 1991-2020 mean value of 39.5^°F (Figure 1).  December 2023 was tied with 1984 and 2021 as the fourth warmest December since records began in 1895.

December Precipitation

Delaware’s statewide precipitation for December 2023 averaged 8.23 inches, 4.38 inches above the 1991-2020 mean of 3.85 inches (Figure 2).  This month’s precipitation was the highest December value since 1895.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly positive across the entire state (Figure 3) with many locations seeing positive anomalies of more than 4^°F.  Precipitation anomalies were highly positive across the entire state, with many stations in Sussex County recording departures of more than five inches (Figure 4).   

National Anomalies

Temperatures were above normal across nearly the entire United States (Figure 5), with anomalies reaching over 10^°F across parts of Minnesota.  Precipitation departures were positive across the Atlantic Coast of the United States (especially in the Mid-Atlantic; Figure 6), while the south-central portion of the country experienced negative precipitation departures. The 500 hPa height pattern for December shows a strong jet stream ridge covering most of North America, contributing to the temperature anomalies found across the entire country (Figure 7).

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