Preliminary data indicates that the statewide average temperature in July was 78.4o F, which is 1.8o F above the 1981-2010 mean value of 76.6o F (Figure 1). The statewide temperature in July 2021 was tied as the 14th warmest since observations began in 1895.
Delaware’s statewide precipitation for July 2021 averaged 5.75 inches, 1.61 inches above the 1981-2010 mean (Figure 2). This placed this month’s precipitation total in the top one-third of all years since 1895.
Statewide Spatial Anomalies
Data from the Delaware Environmental Observing System (DEOS) show that temperature departures were above normal across the majority of the State (Figure 3). Precipitation varied greatly across the State due to localized areas of convective (thunderstorm) activity during the month (Figure 4).
Temperatures were generally below normal across much of the southeastern and southcentral United States, and New England. Warmer than normal temperatures were found across the western one-third of the country, and across the mid-Atlantic region (Figure 5). Some temperature anomalies were greater than 15o F for the month across the Pacific Northwest. Precipitation anomalies varied greatly across the country with dry conditions in much of California and the Northwest United States. Pockets of very wet conditions were found across portions of Texas and New England (Figure 6). The 500 hPa height pattern for July shows a strong jet stream ridge located over the western United States and Canada (Figure 7), leading to the very warm and dry conditions across this region.