Preliminary data indicates that the statewide average temperature in September was 74.0°F, which is 6.0°F above the 1981-2010 mean value of 68.0°F (Figure 1). September 2018 was the warmest September since records for the State began in 1895. The eastern one-third of the United States shared in the extreme warmth, with many cities breaking September temperature records (Figure 2).
Delaware’s statewide precipitation for September 2018 averaged 6.42 inches, 2.45 inches above the 1981-2010 mean (Figure 3). This placed September 2018 as the 11th wettest September on record since 1895.
Statewide Spatial Averages
Data from the Delaware Environmental Observing System (DEOS)show that temperature (Figure 4) departures were positive and large throughout the State. Temperature departures were greater than 5.0°F at many stations across Sussex County. Precipitation departures were positive throughout the State. Departures were as high as 8.6 inches above normal at Stokley.
- September 2023 – Warm with Above Normal Precipitation Across Delaware (2023)
- September 2022 – Near Normal Temperatures and Dry Conditions Across Delaware (2022)
- September 2021 – Warm with Near Normal Precipitation Across Delaware (2021)
- September 2020 – Near Normal Temperature and Precipitation Across Delaware (2020)