Winter Storm Warning
2026-05-06T15:00:00-06:00

* WHAT...Heavy snow expected. Total snow accumulations between 5 and 8 inches with locally up to 12 inches next to the foothills. * WHERE...Fort Collins, Boulder, Denver metro area, and Castle Rock. * WHEN...From 8 PM this evening to 3 PM MDT Wednesday. * IMPACTS...Heavy snow accumulating on trees may result in broken tree limbs, downed powerlines, and scattered power outages. Despite lesser accumulations on roadways, slick and hazardous conditions are still possible for the Wednesday morning commute.

Monocacy River

Last Updated: May 5, 2026

Total streamflow across the Monocacy River was last observed at 594 cfs, and is expected to yield approximately 1,179 acre-ft of water today; about 21% of normal. River levels are low and may signify a drought. Average streamflow for this time of year is 2,870 cfs, with recent peaks last observed on 2021-09-02 when daily discharge volume was observed at 62,500 cfs.

Maximum discharge along the river is currently at the Monocacy River At Jug Bridge Near Frederick reporting a streamflow rate of 293 cfs. However, the streamgauge with the highest stage along the river is the Monocacy River At Bridgeport with a gauge stage of 2.87 ft. This river is monitored from 3 different streamgauging stations along the Monocacy River, the highest being situated at an altitude of 332 ft, the Monocacy River At Bridgeport.

The Monocacy River is a 58-mile-long tributary of the Potomac River that flows through Maryland and Pennsylvania.


15-Day Long Term Forecast


River Details

Last Updated 2026-05-05
Discharge Volume 1,179 ACRE-FT
Streamflow 594.2 cfs
Past 24 Hours: -42.0 cfs (-6.6%)
Percent of Normal 20.7%
Maximum 62,500.0 cfs
2021-09-02
Seasonal Avg 2,870 cfs
       
River Streamflow Levels
Streamgauge Streamflow Gauge Stage 24hr Change (%) % Normal Minimum (cfs) Maximum (cfs) Air Temp Elevation
Monocacy River At Bridgeport
USGS 01639000
58 cfs 2.87 ft 0
Monocacy River At Monocacy Blvd At Frederick
USGS 01642190
243 cfs 1.87 ft -6.9
Monocacy River At Jug Bridge Near Frederick
USGS 01643000
293 cfs 1.99 ft -7.57
Seasonal Discharge Comparison
Maximum Streamflow Discharge
Streamflow Elevation Profile

The Monocacy River is a free-flowing left tributary to the Potomac River, which empties into the Atlantic Ocean via the Chesapeake Bay. The river is 58.5 miles (94.1 km) long, with a drainage area of about 744 square miles (1,930 km2). It is the largest Maryland tributary to the Potomac.
The name "Monocacy" comes from the Shawnee name for the river Monnockkesey, which translates to "river with many bends." (However, another local tradition asserts that "Monocacy" means "well-fenced garden" in an Indian language.) The first town ever settled in Western Maryland, Monocacy, also gets its name from this river.
The Monocacy National Battlefield lies alongside part of the river, marking an 1864 engagement during the American Civil War, the Battle of Monocacy Junction. The Chesapeake and Ohio Canal crosses over the river at the Monocacy Aqueduct, the largest of the 11 aqueducts on the canal.