Preliminary data indicates that the statewide average temperature in September was 71.1°F, which is 3.7°F above the 1981-2010 mean value of 68.0°F (Figure 1). This places September 2019 as the 9th warmest since records began in 1895.
Delaware’s statewide precipitation for September 2019 averaged 1.15 inches, 2.82 inches below the 1981-2010 mean (Figure 2). September 2019 was the 9th driest on record since 1895.
Statewide Spatial Anomalies
Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal throughout the State (Figure 3), with the largest positive anomalies found across northern New Castle County. Precipitation was below normal at every station (Figure 4), with the largest negative anomalies found across New Castle County, where some stations recorded precipitation totals more than 4 inches below the September normal.
Temperatures were far above normal throughout most of the eastern two-thirds of the U.S, where some positive anomalies reached greater than 7°F (Figure 5). In general, precipitation was below normal across the eastern U.S. and much of the country’s southern tier. Only the northern Great Plains and Pacific Northwest saw significantly above normal precipitation (Figure 6). The 500 hPa height pattern for September showed an anomalous ridge over the eastern U.S. (Figure 7), bringing the warm temperatures to that region.
- September 2021 – Warm with Near Normal Precipitation Across Delaware (2021)
- September 2020 – Near Normal Temperature and Precipitation Across Delaware (2020)
- September 2018: Extreme Warmth and Very Wet Across Delaware (2018)
- Warm and Dry Conditions Characterize the 2017 Autumn Season Across Delaware (2017)