August 2020 – Warm and Very Wet Across Delaware

August Temperatures

Preliminary data indicates that the statewide average temperature in August was 77.6^o F, which is 2.7^o F above the 1981-2010 mean value of 74.9^o F (Figure 1).  August 2020 was the 6^th warmest August since observations began in 1895.

August Precipitation

Delaware’s statewide precipitation for August 2020 averaged 7.34 inches, 3.21 inches above the 1981-2010 mean (Figure 2).  The August 2020 precipitation amount was the 17^th wettest since 1895, placing this month in the wettest one-third of all Augusts since the start of observations.

Statewide Spatial Anomalies

Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal throughout the State (Figure 3).  Precipitation anomalies were extreme in several locations with many stations reporting positive anomalies of greater than 7 inches, (Figure 4).  These large precipitation anomalies were primarily the result of Tropical Storm Isaias which crossed Delaware on August 4th and severe thunderstorms which impacted northern Delaware just three days later on August 7^th.

National Anomalies

Temperatures were above normal across most of the western one-third of the country (up to 10^o F) and the Northeast, while below normal temperatures were found across the Great Plains and Midwest (Figure 5).  Precipitation was generally far below normal across the western United States, while much above normal precipitation fell across portions of Arkansas, Louisiana, and the mid-Atlantic Region of the country.   (Figure 6).  The 500 hPa height pattern for August exhibits a ridge dominating the western portion of North America leading to generally warm and dry weather across that region which contributed to the severe wildfire season (Figure 7).

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