Preliminary data indicates that the statewide average temperature in January was 40.1°F, which is 6.0°F above the 1981-2010 mean value of 34.1°F (Figure 1). January 2020 was tied with January of 2007 as the 11th warmest since 1895 in Delaware.
Delaware’s statewide precipitation for January 2020 averaged 3.20 inches, 0.12 inches below the 1981-2010 mean (Figure 2). This placed the January 2020 precipitation amount in the “normal” category for the month.
Statewide Spatial Anomalies
Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were uniformly above normal throughout the State (Figure 3), with some stations more than 6°F above the 30-year mean. Precipitation was below normal across Kent and Sussex Counties, while several stations in New Castle County had small positive precipitation departures (Figure 4).
Temperatures were above normal across the majority of the U.S, with some departures reaching 7° to 10°F in the Northeast (Figure 5). Precipitation varied greatly across the U.S. with very wet conditions across the central States while the extreme southwest remained very dry (Figure 6). The 500 hPa height pattern for January showed a ridge dominating the eastern half of the country (Figure 7), bringing the warm conditions to our region.