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Water Science for Maryland, Delaware and the District of Columbia


Monthly data from five Mid-Atlantic National Weather Service (NWS) stations were used to show the relationship between monthly precipitation and monthly groundwater levels and streamflows. The NWS uses averages of data over the 30-year climate normal period from 1981 through 2010.


September 2018 Precipitation

Precipitation was above normal at the five Mid-Atlantic NWS weather stations. At the two weather stations in Maryland and the weather station in Arlington, Virginia, precipitation was more than double the September average value. The long-term average September 2018 precipitation for the five Mid-Atlantic NWS weather stations is shown next to the September 2018 precipitation in the graph and map below.



The precipitation graph and map show September 2018 precipitation and the departure from the 30-year climate normal.

*The NWS normal (long-term average) period used for determining records is from 1981–2010



National Weather Service MD and DC
National Weather Service DE
Middle Atlantic River Forecast Center (MARFC)

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