2019 Rainfall and Temperature Trends for Delaware

Jarrod O. Miller, Extension Agronomist, jarrod@udel.edu

With corn harvest progressing across the state, it is a good opportunity to observe how summer temperature trends may have played into yields. It is hard to avoid high daytime temperatures in the summer, and your luck is really poor when nighttime temperatures stay above 72°F. This year, any corn pollinating around July 22 underwent a period of higher nighttime temperatures. This could have potentially affected corn planted the last week of May through early June.

At our research station, corn planted on May 2 underwent pollination around July 1, while corn planted on May 16 underwent pollination on July 8. The yields were very different, with the May 2 planting yielding 201 bu/acre, and the May 16 field yielding 146 bushels. This is not a study, but just an observation of events from this season. Next year’s weather will determine whether those who plant later are luckier.

Rainfall trends (Figure 2) are based off a planting date of April 14. In Figure 2, you can see that most parts of the state received similar rainfall, until the beginning of June. At that point, Newark and Dover received more rainfall than the southern part of the state; however, irrigation should have made up for the deficit. In August, most regions, besides Dagsboro, went flat and received very little rainfall until the end of the month. Georgetown did received rainfall, but it appears the readings are not available from the weather station.

For total rainfall (Figure 3), Newark led the state with 24.3 inches since April 14 through September 18. Every other town saw at least 20 inches, besides Georgetown with 18.5 inches.

Figure 1: Statewide temperatures since April 1st.

Figure 2: Statewide rainfall accumulation since April 14th.

Figure 3: Total rainfall by weather station since April 14th.

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