Frost Advisory
2026-10-25T09:00:00-04:00

* WHAT...Temperatures as low as 33 will result in frost formation. * WHERE...Portions of central, northeast, and northern Maryland and central, northern, and northwest Virginia. * WHEN...Until 9 AM EDT this morning. * IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered.

Realtime Data

Virginia

Explore Interactive Map

Frost Advisory
Until 2026-10-25T09:00:00-04:00 • National Weather Service
* WHAT...Temperatures as low as 33 will result in frost formation. * WHERE...Portions of central, northeast, and northern Maryland and central, northern, and northwest Virginia. * WHEN...Until 9 AM EDT this morning. * IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered.

DIFFICULT RUN NEAR GREAT FALLS, VA

Realtime Data • Report • Conditions

15

Discharge (cfs)

2.7

Gauge Height (ft)

USGS 01646000

Streamflow discharge was last observed at 15 cfs, and a gauge height of 2.70 feet. With the % decrease since yesterday, the streamflow average over the past 10 days is 22 .

Weather today, Tomorrow,

The run is also impacted by the nearby Great Falls Dam, which regulates flow downstream. Seasonally, the flow tends to be highest in the spring due to snowmelt and lower in the summer and fall. Interesting facts about the hydrology of this area include its importance as a source of drinking water for the Washington, DC area and its role in providing habitat for a variety of aquatic species, including the threatened eastern hellbender salamander.

October 25, 2026

Elevation	157.0 ft
Last Updated
Gage height, ft	2.7 ft
Nitrate plus nitrite, water, in situ, mg/L as N	1.78 mg/l as N
Streamflow, ft³/s	14.8 ft3/s
Specific conductance, water, unfiltered, microsiemens per centimeter at 25°C	306.0 uS/cm @25C
Dissolved oxygen, water, unfiltered, mg/L	10.2 mg/l
Turbidity, water, unfiltered, monochrome near infra-red LED light, 780-900 nm, detection angle 90 ±2.5°, formazin nephelometric units (FNU)	3.9 FNU
pH, water, unfiltered, field, standard units	7.4 std units
Temperature, water, °C	10.6 deg C
Percent of Normal	83%
Year Over Year Average	18 cfs
24hr Flow Prediction	cfs
Maximum Recorded	8,640 cfs
Geolocation	38.98, -77.25

SNOFLO^®

Difficult Run Near Great Falls, Va Realtime Data

DIFFICULT RUN NEAR GREAT FALLS, VA

Realtime Data • Report • Conditions

15

Discharge (cfs)

2.7

Gauge Height (ft)

October 25, 2026

Seasonal Comparison

Oceanic Nino Index

SNOFLO®

Difficult Run Near Great Falls, Va Realtime Data

DIFFICULT RUN NEAR GREAT FALLS, VA

Realtime Data • Report • Conditions

15

Discharge (cfs)

2.7

Gauge Height (ft)

October 25, 2026

Seasonal Comparison

Oceanic Nino Index

$4.99

$3.99

Per Month

SNOFLO^®