Water Temperature of Difficult Run in McLean, VA

Current Water Temperature

74.8°F

Measurement Time: Tuesday, July 28, 2026, 3:15 AM EDT

Temperature Locations

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Local Points of Interest

Great Falls Park; Great Falls, VA

Difficult Run

Station Name: DIFFICULT RUN NEAR GREAT FALLS, VA
Data Source: Water Data - usgc.gov

Elevation Above Sea Level: 184 feet

Nearest Address:
9200 Old Dominion Dr
McLean, VA 22102
Fairfax County

GPS Coordinates: 38.97594346, -77.24581439

Nearby Water Temperatures

Dead Run, McLean, VA (3.9 mi)
Difficult Run, Oakton, VA (7.8 mi)
Sligo Creek, Takoma Park, MD (13 mi)
Washington Channel, Washington, DC (14 mi)
Paint Branch, Calverton, MD (15.6 mi)
Northeast Branch Anacostia River, Riverdale Park, MD (17.2 mi)
Patuxent River, Brighton, MD (19.8 mi)
Potomac River, Point of Rocks, MD (26 mi)
Carroll Creek, Frederick, MD (32.5 mi)
Carroll Creek, Frederick, MD (33.5 mi)
Scotts Level Branch, Milford Mill, MD (37.2 mi)
Northwest Harbor, Baltimore, MD (41 mi)
Spout Run, Boyce, VA (41.2 mi)
Severn River, Annapolis, MD (41.2 mi)
Chesapeake Bay, Annapolis, MD (42.9 mi)

Weather for McLean, Virginia

Current Weather

72.3°F
Sunny
Sunny
61.7°F
76.5°F
87%
SSE 6 mph
12.6 mph
72.3°F
68.1°F
0 in
0%
5 mi
1005 mbar
0.1

Five Day Weather Forecast

Sunny
Tue
H: 96°F
L: 68°F
Partly Cloudy
Wed
H: 82°F
L: 66°F
Patchy rain nearby
Thu
H: 80°F
L: 67°F
Partly Cloudy
Fri
H: 84°F
L: 63°F
Sunny
Sat
H: 87°F
L: 67°F

Air Quality

AQI: 1 - Good
PM2.5: 17.8 μg/m3
PM10: 18 μg/m3
Carbon Monoxide: 196 μg/m3
Nitrogen Dioxide: 10.4 μg/m3
Sulphur Dioxide: 2.2 μg/m3
Ozone: 58 μg/m3

Astronomical

Sunrise: 6:06 AM
Sun Transit: 1:15 PM
Sunset: 8:24 PM
Daylight: 14 hrs 18 mins
Moonrise: 8:11 PM
Moon Transit: 12:10 AM
Moonset: 4:51 AM
Moon Phase: Full
Moon Illumination: 99.7%

Best Times for Fishing or Hunting

Major Periods

12:00 AM - 12:00 AM
1:50 PM - 4:20 PM

Minor Periods

7:41 PM - 9:11 PM
4:21 AM - 5:51 AM

Action Rating: 4 out of 5

Small Craft Advisory issued July 27 at 9:45PM EDT until July 28 at 8:00PM EDT by NWS Baltimore MD/Washington DC

Effective: Mon July 27, 2026, 9:45 PM
Expires: Tue July 28, 2026, 5:45 AM

* WHAT...South winds 10 to 15 kt with gusts up to 25 kt expected. * WHERE...Tidal Potomac River from Key Bridge to Cobb Island MD. * WHEN...From 1 PM to 8 PM EDT Tuesday. * IMPACTS...Conditions will be hazardous to small craft.

Inexperienced mariners, especially those operating smaller vessels, should avoid navigating in hazardous conditions.
Tuesday, July 28, 2026

Weather Forecast

Sunny
96.1°F
68.3°F
78.9°F
74%
0.28 in
66%
0%
8.5 mph
8.1


Air Quality

AQI: 2 - Moderate
PM2.5: 18.01 μg/m3
PM10: 18.38 μg/m3
Carbon Monoxide: 209.67 μg/m3
Nitrogen Dioxide: 9.66 μg/m3
Sulphur Dioxide: 1.75 μg/m3
Ozone: 76.58 μg/m3

Astronomical

Sunrise: 6:06 AM
Sun Transit: 1:15 PM
Sunset: 8:24 PM
Daylight: 14 hrs 18 mins
Moonrise: 8:11 PM
Moon Transit: 12:10 AM
Moonset: 4:51 AM
Moon Phase: Full
Moon Illumination: 99.7%

Best Times for Fishing or Hunting

Major Periods

12:00 AM - 12:00 AM
1:50 PM - 4:20 PM

Minor Periods

7:41 PM - 9:11 PM
4:21 AM - 5:51 AM

Action Rating: 4 out of 5

Wednesday, July 29, 2026

Weather Forecast

Partly Cloudy
82.2°F
65.9°F
72.4°F
75%
0.01 in
21%
0%
11.6 mph
7.7


Air Quality

AQI: 1 - Good
PM2.5: 4.11 μg/m3
PM10: 4.15 μg/m3
Carbon Monoxide: 156.54 μg/m3
Nitrogen Dioxide: 3.92 μg/m3
Sulphur Dioxide: 0.93 μg/m3
Ozone: 70.79 μg/m3

Astronomical

Sunrise: 6:07 AM
Sun Transit: 1:15 PM
Sunset: 8:23 PM
Daylight: 14 hrs 16 mins
Moonrise: 8:42 PM
Moon Transit: 1:00 AM
Moonset: 5:54 AM
Moon Phase: Full
Moon Illumination: 99.7%

Best Times for Fishing or Hunting

Major Periods

12:30 AM - 3:00 AM
2:38 PM - 5:08 PM

Minor Periods

8:12 PM - 9:42 PM
5:24 AM - 6:54 AM

Action Rating: 4 out of 5

Thursday, July 30, 2026

Weather Forecast

Patchy rain nearby
80°F
66.8°F
72.2°F
75%
0.15 in
74%
0%
11.4 mph
5.1


Air Quality

AQI: 1 - Good
PM2.5: 2.63 μg/m3
PM10: 2.7 μg/m3
Carbon Monoxide: 130.04 μg/m3
Nitrogen Dioxide: 3.8 μg/m3
Sulphur Dioxide: 1.02 μg/m3
Ozone: 70.04 μg/m3

Astronomical

Sunrise: 6:08 AM
Sun Transit: 1:15 PM
Sunset: 8:22 PM
Daylight: 14 hrs 14 mins
Moonrise: 9:08 PM
Moon Transit: 1:45 AM
Moonset: 6:58 AM
Moon Phase: Full
Moon Illumination: 97.1%

Best Times for Fishing or Hunting

Major Periods

1:15 AM - 3:45 AM
3:23 PM - 5:53 PM

Minor Periods

8:38 PM - 10:08 PM
6:28 AM - 7:58 AM

Action Rating: 5 out of 5

Friday, July 31, 2026

Weather Forecast

Partly Cloudy
83.6°F
63.2°F
73.3°F
72%
0.01 in
22%
0%
5.8 mph
6.4


Air Quality

AQI: 1 - Good
PM2.5: 4.33 μg/m3
PM10: 4.43 μg/m3
Carbon Monoxide: 156.15 μg/m3
Nitrogen Dioxide: 4.9 μg/m3
Sulphur Dioxide: 1.08 μg/m3
Ozone: 74.67 μg/m3

Astronomical

Sunrise: 6:09 AM
Sun Transit: 1:15 PM
Sunset: 8:21 PM
Daylight: 14 hrs 12 mins
Moonrise: 9:32 PM
Moon Transit: 2:30 AM
Moonset: 8:02 AM
Moon Phase: Full
Moon Illumination: 92.0%

Best Times for Fishing or Hunting

Major Periods

2:00 AM - 4:30 AM
4:07 PM - 6:37 PM

Minor Periods

9:02 PM - 10:32 PM
7:32 AM - 9:02 AM

Action Rating: 3 out of 5

Saturday, August 1, 2026

Weather Forecast

Sunny
87.3°F
66.8°F
76.6°F
68%
0 in
17%
0%
9.2 mph
8


Air Quality

AQI: 1 - Good
PM2.5: 5.01 μg/m3
PM10: 5.03 μg/m3
Carbon Monoxide: 239.33 μg/m3
Nitrogen Dioxide: 9.47 μg/m3
Sulphur Dioxide: 0.92 μg/m3
Ozone: 44.11 μg/m3

Astronomical

Sunrise: 6:10 AM
Sun Transit: 1:15 PM
Sunset: 8:20 PM
Daylight: 14 hrs 10 mins
Moonrise: 9:54 PM
Moon Transit: 3:13 AM
Moonset: 9:05 AM
Moon Phase: Waning Gibbous
Moon Illumination: 84.9%

Best Times for Fishing or Hunting

Major Periods

2:43 AM - 5:13 AM
4:50 PM - 7:20 PM

Minor Periods

9:24 PM - 10:54 PM
8:35 AM - 10:05 AM

Action Rating: 2 out of 5

The times presented here are based upon the solunar theory, which is the idea that the movements of fish and other animals are affected by the location of the sun and moon. The major periods are believed to be the times of the greatest animal activity and occur when the moon is directly overhead or underfoot (lunar transits). The minor periods also see increased activity and occur when the moon is rising or setting. The strongest activity occurs during full or new moons, and the weakest during quarter or three quarter moons. This is indicated by the Action Rating.

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