April 2023 – Very Warm with Above Normal Precipitation Across Delaware

April Temperatures

Preliminary data indicates that the statewide average temperature in April was 58.8^o F, which is 4.4^o F above the 1991-2020 mean value of 54.4^o F (Figure 1).  April 2023 was the 2^nd warmest since observations began in 1895.

April Precipitation

Delaware’s statewide precipitation for April 2023 averaged 5.65 inches, 2.17 inches above the 1991-2020 mean of 3.48 inches (Figure 2).  This month’s precipitation was tied with 1928 as the 7^th wettest since 1895.  Interestingly, most of the April precipitation fell during the final three days of the month. 

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 anomalies of nearly 5^o F.  Precipitation anomalies were consistently positive across the entire state, with many stations recording departures of more than four inches, especially in Kent County (Figure 4).   

National Anomalies

Temperatures were generally above normal across the northeastern United States (Figure 5), while the north-central and northwestern portions of the country saw below normal temperatures (Figure 5).  Precipitation departures were mixed across the country, with the largest positive precipitation anomalies found along the Atlantic and Gulf Coast regions (Figure 6). The 500 hPa height pattern for April shows a weak jet stream trough covering most of the western two-thirds of the United States, while much of the eastern one-third of the country was covered by a jet stream ridge, contributing to the temperature anomalies found across these regions (Figure 7).

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