Maryland Climate Bulletin: September 2025

[dallen7908]

Hi all,

MD Climate Bulletin for September 2025 follows: 

"We are pleased to share the Maryland Climate Bulletin for September
2025, which includes sea surface temperatures for the Chesapeake Bay
and the state's coastal waters. However, due to the ongoing federal
government shutdown, the availability of the main data source we use
for the Bulletin has been affected. The regular production of the
bulletin is only possible thanks to the hard work and data provided by
our friends at NOAA National Centers for Environmental Information,
the CoastWatch East Coast Node, the Institutions involved in the U.S.
Drought Monitor, and the U.S. Geological Survey's Water Watch.

You can access the Bulletin from the following link:

https://mdsco.umd.edu/Bulletin/bulletin_mdsco_current.pdf

Points to highlight are:

1) Statewide averages indicate that September 2025 was warmer and
drier than normal (i.e., 1991-2020 averages).

2) Regionally, the mean temperature was warmer than normal over the
majority of the state. Warmer-than-normal anomalies appeared over the
northern half of the state, especially over parts of Carroll,
Frederick, and Washington counties (around 1.0°F). Colder-than-normal
conditions appeared over the southern counties to both sides of the
Bay, particularly over Charles County (around 1.0°F below).

3) Precipitation was below normal for the majority of the state,
notably over Frederick and Washington counties (2.0 to 3.0 inches
deficit), and over Garrett, Allegany, Carroll, Montgomery, Howard,
Baltimore, Harford, Cecil, Charles, and Prince George’s counties (1.0
to 2.0 inches deficit). Above normal precipitation appeared over some
areas in the Eastern Shore, over Queen Anne’s, Kent, and Worcester
counties (larger than 2 inches), as well as over portions of
Dorchester and Wicomico counties (1.0 to 2.0 inches). The first of
these regions, over the western states, received 25 to 50% less
precipitation than normal, while the regions in the Eastern Shore got
25 to 50% more precipitation than normal for the month.

4) Drought conditions intensified in September, primarily in the
western counties. While the extent of the state affected by drought
diminished from 70% to 50%, Moderate Drought conditions affected
Garrett, Allegany, and Washington counties along the limits with West
Virginia, as well as western and central Montgomery County. Severe
Drought conditions also developed over the western counties, and even
Extreme Drought conditions started to creep over the southern tip of
Garrett County. The rest of these counties were under Abnormally Dry
conditions, which also affected Frederick, Carroll, Baltimore, Howard,
Prince George’s, Charles, Calvert, Saint Mary’s, and Caroline. Several
streams and rivers in the Piedmont and western Maryland had
Below-normal streamflow, with a few experiencing Much-below-normal
streamflow.

5) The Chesapeake Bay sea surface temperatures (SST) in September 2025
ranged between 73 and 78°F, marking the second consecutive month they
remained below their 2007–2020 mean across the entire region. A
distinct north-to-south gradient defined the magnitude of the cold
anomalies. The most significant deficit (3–4°F below average) was
recorded in the southeastern Lower Bay, encompassing Tangier Sound
waters off Somerset, Wicomico, and Dorchester counties. Moving
northward, along the coasts of Talbot and Queen Ann counties up to
Eastern Bay, the anomalies lessened to 2–3°F below the mean. The
waters off Kent and Baltimore counties and farther northward in the
Upper Bay, showed the smallest cold anomalies (1–2°F below).
Chincoteague Bay temperatures were also notably colder than normal
(2–3°F below). The all-basin mean temperature of 74.0°F was still
warmer than the coldest September in the 19-year dataset (2007-2025),
which recorded 72.8°F in 2009.

Please refer to the bulletin for more details. The bulletin is issued
once per month and shows the state's recent monthly surface
temperature and precipitation conditions in a simple format, helping
Marylanders better understand regional climate variations.

Please help disseminate this bulletin.

Thanks,

Alfredo
.............................................
Alfredo Ruiz-Barradas, PhD
Associate Research Professor
Maryland State Climatologist"