Piney Run at Reston (Northern Sector Pond 1)
0.7 mi- Level
- 345 ft
Reading from Sat 4:55 PM · NWS gauge page
Observed 5:40 PM EDT at KIAD
Great Falls Crossing, VA weather
Sunny and 61°16°.
Today: low 38°3° (likely 37°3° to 38°3°), high 63°17° (likely 61°16° to 64°18°).
Now 61°16°
Sunny
- Wind
- 6 mph9 km/h
- From the east. Up to 6 mph9 km/h through 6 AM
- Dew point
- 39°4°
- Comfortable
- UV tomorrow
- 4Moderate
- Moderate 11 AM–5 PM · peak 4
- Air quality
- 32Good
- Ozone · tomorrow moderate
- Pressure
- 30.5 inHg1033 hPa
- Steady over the last 3 h
Next 2 hours
No precipitation expected in the next 2 hours.
From forecast models
Next 48 hours
About the same as this time yesterday (63°17° then, 62°17° now)
Good hours for
TonightDown to 41°5° by 4 AM · Clear
Tomorrow morningUp to 56°13° by 11 AM · Clear
Tomorrow afternoonUp to 65°18° by 3 PM · Clear
Tomorrow nightDown to 40°4° by 5 AM · Clear
Monday morningUp to 56°13° by 11 AM · Clear
Monday afternoonUp to 69°21° by 3 PM · Clear
| Hour | Conditions | Temperature | Feels like | Precipitation | Wind | Humidity | Cloud cover | UV index |
|---|---|---|---|---|---|---|---|---|
| Sat 6p | Mostly clear | 59°15° (likely 56°13° to 61°16°) | 59°15° | 0% | 5 mph8 km/h from E, gusts 11 mph17 km/h | 47% | 23% | 0 |
| Sat 7p | Mostly clear | 55°13° (likely 53°12° to 56°13°) | 55°13° | 0% | 3 mph5 km/h from E, gusts 8 mph12 km/h | 55% | 20% | 0 |
| Sat 8p | Clear | 51°11° (likely 50°10° to 54°12°) | 51°11° | 0% | 3 mph5 km/h from E, gusts 8 mph13 km/h | 68% | 14% | 0 |
| Sat 9p | Clear | 49°9° (likely 49°9° to 51°11°) | 48°9° | 0% | 3 mph5 km/h from E, gusts 8 mph12 km/h | 74% | 11% | 0 |
| Sat 10p | Clear | 48°9° (likely 47°8° to 50°10°) | 47°8° | 0% | 3 mph5 km/h from E, gusts 7 mph11 km/h | 77% | 0% | 0 |
| Sat 11p | Clear | 46°8° (likely 46°8° to 48°9°) | 46°8° | 0% | 2 mph3 km/h from E, gusts 7 mph11 km/h | 83% | 13% | 0 |
| Sun 12a | Clear | 45°7° (likely 45°7° to 47°8°) | 45°7° | 0% | 2 mph3 km/h from E, gusts 6 mph9 km/h | 86% | 15% | 0 |
| Sun 1a | Clear | 44°7° (likely 44°7° to 46°8°) | 44°7° | 0% | 2 mph3 km/h from E, gusts 4 mph6 km/h | 89% | 15% | 0 |
| Sun 2a | Clear | 43°6° (likely 43°6° to 46°8°) | 43°6° | 0% | 2 mph3 km/h from NE, gusts 4 mph6 km/h | 96% | 14% | 0 |
| Sun 3a | Clear | 42°6° (likely 42°6° to 45°7°) | 42°6° | 0% | 1 mph2 km/h from NE, gusts 3 mph5 km/h | 96% | 6% | 0 |
| Sun 4a | Clear | 41°5° (likely 41°5° to 44°7°) | 41°5° | 0% | 1 mph2 km/h from N, gusts 2 mph4 km/h | 96% | 5% | 0 |
| Sun 5a | Clear | 41°5° (likely 41°5° to 43°6°) | 41°5° | 0% | 1 mph2 km/h from N, gusts 3 mph4 km/h | 92% | 14% | 0 |
| Sun 6a | Mostly clear | 40°4° (likely 40°4° to 43°6°) | 40°4° | 0% | 2 mph3 km/h from N, gusts 3 mph4 km/h | 96% | 18% | 0 |
| Sun 7a | Mostly sunny | 39°4° (likely 39°4° to 42°6°) | 39°4° | 0% | 2 mph3 km/h from N, gusts 3 mph5 km/h | 96% | 26% | 0 |
| Sun 8a | Sunny | 40°4° (likely 38°3° to 43°6°) | 40°4° | 0% | 2 mph3 km/h from N, gusts 3 mph4 km/h | 96% | 14% | 0 |
| Sun 9a | Mostly sunny | 44°7° (likely 44°7° to 47°8°) | 44°7° | 0% | 1 mph2 km/h from N, gusts 3 mph5 km/h | 93% | 8% | 1 |
| Sun 10a | Sunny | 51°11° (likely 51°11° to 54°12°) | 51°11° | 0% | 2 mph3 km/h from NE, gusts 6 mph9 km/h | 77% | 3% | 2 |
| Sun 11a | Sunny | 56°13° (likely 56°13° to 58°14°) | 56°13° | 0% | 1 mph2 km/h from E, gusts 6 mph9 km/h | 66% | 4% | 3 |
| Sun 12p | Sunny | 59°15° (likely 59°15° to 62°17°) | 59°15° | 0% | 1 mph2 km/h from E, gusts 4 mph7 km/h | 60% | 3% | 4 |
| Sun 1p | Mostly sunny | 61°16° (likely 61°16° to 64°18°) | 61°16° | 0% | 2 mph3 km/h from SE, gusts 5 mph7 km/h | 53% | 16% | 4 |
| Sun 2p | Mostly sunny | 63°17° (likely 63°17° to 65°18°) | 63°17° | 0% | 2 mph3 km/h from SE, gusts 6 mph10 km/h | 50% | 10% | 4 |
| Sun 3p | Sunny | 65°18° (likely 63°17° to 66°19°) | 65°18° | 0% | 2 mph3 km/h from SE, gusts 7 mph11 km/h | 46% | 9% | 4 |
| Sun 4p | Sunny | 64°18° (likely 63°17° to 66°19°) | 64°18° | 0% | 2 mph3 km/h from SE, gusts 7 mph12 km/h | 48% | 10% | 3 |
| Sun 5p | Sunny | 64°18° (likely 62°17° to 65°18°) | 64°18° | 0% | 1 mph2 km/h from S, gusts 6 mph9 km/h | 48% | 11% | 1 |
| Sun 6p | Clear | 61°16° (likely 59°15° to 62°17°) | 61°16° | 0% | 1 mph2 km/h from N, gusts 6 mph10 km/h | 53% | 2% | 0 |
| Sun 7p | Clear | 58°14° (likely 55°13° to 58°14°) | 58°14° | 0% | 1 mph2 km/h from SE, gusts 5 mph7 km/h | 59% | 0% | 0 |
| Sun 8p | Clear | 53°12° (likely 52°11° to 55°13°) | 53°12° | 0% | 1 mph2 km/h from SE, gusts 4 mph7 km/h | 74% | 0% | 0 |
| Sun 9p | Clear | 50°10° (likely 50°10° to 54°12°) | 50°10° | 0% | 1 mph2 km/h from S, gusts 5 mph7 km/h | 80% | 0% | 0 |
| Sun 10p | Clear | 48°9° (likely 48°9° to 51°11°) | 48°9° | 0% | 1 mph2 km/h from S, gusts 4 mph6 km/h | 86% | 0% | 0 |
| Sun 11p | Clear | 46°8° (likely 46°8° to 49°9°) | 46°8° | 0% | 1 mph2 km/h from S, gusts 4 mph7 km/h | 93% | 1% | 0 |
| Mon 12a | Clear | 45°7° (likely 45°7° to 48°9°) | 45°7° | 0% | 1 mph2 km/h from S, gusts 4 mph6 km/h | 93% | 0% | 0 |
| Mon 1a | Clear | 45°7° (likely 45°7° to 47°8°) | 45°7° | 0% | 2 mph3 km/h from W, gusts 4 mph7 km/h | 93% | 1% | 0 |
| Mon 2a | Clear | 43°6° (likely 43°6° to 46°8°) | 43°6° | 0% | 1 mph2 km/h from W, gusts 4 mph6 km/h | 96% | 1% | 0 |
| Mon 3a | Clear | 42°6° (likely 42°6° to 45°7°) | 42°6° | 0% | 2 mph3 km/h from W, gusts 5 mph9 km/h | 100% | 7% | 0 |
| Mon 4a | Clear | 41°5° (likely 41°5° to 45°7°) | 41°5° | 0% | 1 mph2 km/h from W, gusts 6 mph9 km/h | 100% | 13% | 0 |
| Mon 5a | Clear | 40°4° (likely 40°4° to 44°7°) | 40°4° | 0% | 2 mph3 km/h from W, gusts 7 mph11 km/h | 100% | 15% | 0 |
| Mon 6a | Clear | 39°4° (likely 39°4° to 44°7°) | 39°4° | 0% | 2 mph3 km/h from W, gusts 6 mph10 km/h | 100% | 21% | 0 |
| Mon 7a | Sunny | 39°4° (likely 39°4° to 42°6°) | 39°4° | 0% | 2 mph3 km/h from W, gusts 5 mph8 km/h | 100% | 23% | 0 |
| Mon 8a | Sunny | 39°4° (likely 39°4° to 43°6°) | 39°4° | 0% | 2 mph3 km/h from W, gusts 5 mph8 km/h | 100% | 23% | 0 |
| Mon 9a | Sunny | 43°6° (likely 42°6° to 48°9°) | 43°6° | 0% | 2 mph3 km/h from NW, gusts 5 mph8 km/h | 93% | 21% | 1 |
| Mon 10a | Sunny | 50°10° (likely 50°10° to 55°13°) | 50°10° | 0% | 2 mph3 km/h from W, gusts 8 mph13 km/h | 80% | 6% | 2 |
| Mon 11a | Sunny | 56°13° (likely 56°13° to 60°16°) | 56°13° | 0% | 3 mph5 km/h from NW, gusts 8 mph13 km/h | 66% | 1% | 3 |
| Mon 12p | Sunny | 60°16° (likely 60°16° to 63°17°) | 60°16° | 0% | 5 mph8 km/h from NW, gusts 9 mph14 km/h | 58% | 2% | 4 |
| Mon 1p | Sunny | 64°18° (likely 64°18° to 66°19°) | 64°18° | 0% | 6 mph10 km/h from NW, gusts 9 mph14 km/h | 50% | 0% | 4 |
| Mon 2p | Sunny | 67°19° (likely 66°19° to 68°20°) | 67°19° | 0% | 6 mph10 km/h from NW, gusts 10 mph17 km/h | 47% | 0% | 4 |
| Mon 3p | Sunny | 69°21° (likely 66°19° to 69°21°) | 69°21° | 0% | 7 mph11 km/h from NW, gusts 12 mph19 km/h | 45% | 0% | 4 |
| Mon 4p | Sunny | 69°21° (likely 67°19° to 69°21°) | 69°21° | 0% | 6 mph10 km/h from NW, gusts 12 mph19 km/h | 45% | 0% | 3 |
| Mon 5p | Sunny | 69°21° (likely 66°19° to 69°21°) | 69°21° | 0% | 5 mph8 km/h from NW, gusts 10 mph17 km/h | 47% | 0% | 1 |
Days ahead
Shaded: typical range for these dates (1991–2020)
Today, Oct 24. Mostly sunny. High 63°17°, low 38°3°. Typical 65°18° / 42°6°. Dry. Mostly agree.
Evening
6 PM–midnight
Clear, 51°11°Dry
Overnight
midnight–6 AM
Clear, 41°5°Dry
Official NWS forecast
Tonight: Mostly clear, with a low around 38. East wind 1 to 5 mph.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
- High, likely
- 61°16°–64°18°
- Low, likely
- 37°3°–38°3°
- Typical high / low
- 65°18° / 42°6°
- Wind
- 6 mph10 km/h, gusts 13 mph21 km/h
- UV peak
- 4
Tomorrow, Oct 25. Mostly sunny. High 65°18°, low 38°3°. Typical 64°18° / 42°6°. Dry. Mostly agree.
Morning
6 AM–noon
Mostly sunny, 40°4°Dry
Afternoon
noon–6 PM
Sunny, 65°18°Dry
Evening
6 PM–midnight
Clear, 53°12°Dry
Overnight
midnight–6 AM
Clear, 40°4°Dry
Official NWS forecast
Day: Sunny, with a high near 65. East wind around 2 mph.
Night: Clear, with a low around 38. Southwest wind around 2 mph.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
- High, likely
- 63°17°–66°19°
- Low, likely
- 38°3°–42°6°
- Typical high / low
- 64°18° / 42°6°
- Wind
- 6 mph9 km/h
- UV peak
- 4
Monday, Oct 26. Mostly sunny. High 70°21°, low 47°8°. Typical 64°18° / 41°5°. Dry. Forecasts agree.
Morning
6 AM–noon
Sunny, 39°4°Dry
Afternoon
noon–6 PM
Sunny, 69°21°Dry
Evening
6 PM–midnight
Clear, 56°13°Dry
Overnight
midnight–6 AM
Clear, 48°9°Dry
Official NWS forecast
Day: Sunny, with a high near 70. Northwest wind 2 to 7 mph.
Night: Mostly clear, with a low around 47. Northwest wind 1 to 5 mph.
Forecasts agreeIndependent forecasts are close; the range is narrow.
- High, likely
- 67°19°–70°21°
- Low, likely
- 38°3°–47°8°
- Typical high / low
- 64°18° / 41°5°
- Wind
- 7 mph11 km/h, gusts 15 mph23 km/h
- UV peak
- 4
Tuesday, Oct 27. Mostly sunny. High 68°20°, low 46°8°. Typical 64°18° / 41°5°. Dry. Mostly agree.
Morning
6 AM–noon
Sunny, 48°9°Dry
Afternoon
noon–6 PM
Sunny, 67°19°Dry
Evening
6 PM–midnight
Clear, 57°14°Dry
Overnight
midnight–6 AM
Cloudy, 47°8°Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Sunny, with a high near 68.
Night: Mostly clear, with a low around 46.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
- High, likely
- 66°19°–68°20°
- Low, likely
- 44°7°–50°10°
- Typical high / low
- 64°18° / 41°5°
- Wind
- 8 mph13 km/h, gusts 19 mph30 km/h
- UV peak
- 4
Wednesday, Oct 28. Cloudy. High 65°18°, low 48°9°. Typical 64°18° / 41°5°. Dry. Mostly agree.
Morning
6 AM–noon
Cloudy, 48°9°Dry
Afternoon
noon–6 PM
Cloudy, 65°18°Dry
Evening
6 PM–midnight
Cloudy, 56°13°Dry
Overnight
midnight–6 AM
Cloudy, 49°9°Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Partly sunny, with a high near 65.
Night: Mostly cloudy, with a low around 48.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
- High, likely
- 63°17°–66°19°
- Low, likely
- 44°7°–48°9°
- Typical high / low
- 64°18° / 41°5°
- Wind
- 8 mph12 km/h, gusts 17 mph28 km/h
- UV peak
- 4
Thursday, Oct 29. Cloudy. High 70°21°, low 49°9°. Typical 63°17° / 40°4°. Dry. Mostly agree.
Morning
6 AM–noon
Cloudy, 48°9°Dry
Afternoon
noon–6 PM
Sunny, 69°20°Dry
Evening
6 PM–midnight
Clear, 58°15°Dry
Overnight
midnight–6 AM
Clear, 49°9°Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Mostly sunny, with a high near 70.
Night: Mostly clear, with a low around 49.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
- High, likely
- 67°19°–71°22°
- Low, likely
- 46°8°–49°9°
- Typical high / low
- 63°17° / 40°4°
- Wind
- 6 mph9 km/h, gusts 22 mph36 km/h
- UV peak
- 4
Friday, Oct 30. Mostly sunny. High 74°23°, low 50°10°. Typical 63°17° / 40°4°. Dry. Forecasts agree.
Morning
6 AM–noon
Sunny, 48°9°Dry
Afternoon
noon–6 PM
Sunny, 74°24°Dry
Evening
6 PM–midnight
Clear, 62°17°Dry
Overnight
midnight–6 AM
Mostly clear, 50°10°Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Sunny, with a high near 74.
Night: Mostly clear, with a low around 50.
Forecasts agreeIndependent forecasts are close; the range is narrow.
- High, likely
- 74°23°–75°24°
- Low, likely
- 44°7°–50°10°
- Typical high / low
- 63°17° / 40°4°
- Wind
- 7 mph10 km/h, gusts 26 mph41 km/h
- UV peak
- 4
Saturday, Oct 31. Partly sunny. High 71°22°, low 50°10°. Typical 62°17° / 40°4°. Dry. Forecasts differ.
Morning
6 AM–noon
Mostly sunny, 48°9°Dry
Afternoon
noon–6 PM
Partly sunny, 71°22°Dry
Evening
6 PM–midnight
Cloudy, 59°15°Dry
Overnight
midnight–6 AM
Cloudy, 55°13°Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Mostly sunny, with a high near 71.
Forecasts differIndependent forecasts disagree; expect changes and plan for the range.
- High, likely
- 65°18°–73°23°
- Low, likely
- 45°7°–54°12°
- Typical high / low
- 62°17° / 40°4°
- Wind
- 7 mph11 km/h, gusts 27 mph44 km/h
- UV peak
- 4
Sunday, Nov 1. Drizzle. High 69°21°, low 54°12°. Typical 62°17° / 40°4°. Rain 0.03 in0.8 mm, 30% chance. Forecasts differ.
Morning
6 AM–noon
Cloudy, 55°13°Dry
Afternoon
noon–6 PM
Drizzle, 68°20°30% chance · 0.02 in0.4 mm
Evening
6 PM–midnight
Drizzle, 64°18°30% chance · 0.06 in1.4 mm
Overnight
midnight–6 AM
Drizzle, 62°17°30% chance · 0.08 in1.9 mm
Hours this far out come from computer models only.
The National Weather Service writes about seven days ahead; this day is our model forecast only.
Forecasts differIndependent forecasts disagree; expect changes and plan for the range.
- High, likely
- 64°18°–74°23°
- Low, likely
- 50°10°–57°14°
- Typical high / low
- 62°17° / 40°4°
- Wind
- 10 mph15 km/h, gusts 22 mph36 km/h
- UV peak
- 2
Monday, Nov 2. Drizzle. High 71°22°, low 58°14°. Typical 62°17° / 39°4°. Rain 0.43 in11 mm, 30% chance. Forecasts differ.
Morning
6 AM–noon
Drizzle, 63°17°30% chance · 0.02 in0.5 mm
Afternoon
noon–6 PM
Drizzle, 71°22°Dry
Evening
6 PM–midnight
Drizzle, 63°17°Dry
Hours this far out come from computer models only.
The National Weather Service writes about seven days ahead; this day is our model forecast only.
Forecasts differIndependent forecasts disagree; expect changes and plan for the range.
- High, likely
- 63°17°–78°26°
- Low, likely
- 52°11°–66°19°
- Typical high / low
- 62°17° / 39°4°
- Wind
- 16 mph26 km/h, gusts 37 mph59 km/h
The outlook
Today
Dry, high 63°, low 38°.
Tomorrow
Dry, high 65°, low 38°.
Monday
Dry, high 70°, low 47°, warming up.
Rest of week
Mostly dry, highs 65–74°.
Want the meteorologists’ reasoning? Read the NWS forecast discussion (LWX) (opens in a new tab)
What changed since yesterday
No meaningful changes from yesterday’s forecast.
Radar
Radar data: NOAA MRMS, rendered by forecast.blue
Radar loads when scrolled into view
Rivers
NOAA river gauges within 25 mi
Colvin Run at Lake Fairfax near Reston
1.2 mi- Level
- 262 ft
Reading from Sat 11:15 AM · NWS gauge page
Difficult Run at Browns Mill Road / Wolf Trap
2.7 mi- Level
- 194 ft
Reading from Sat 2:05 PM · NWS gauge page
Difficult Run near Great Falls
4.2 mi- Level
- 2.7 ft
- Flow
- 15 cfs
Reading from Sat 4:15 PM · NWS gauge page
For your home
What this week’s weather means for heating, cooling, pipes and fresh air.
Heating this week
About 68% less heating than a typical week.
This week 28Typical 88
Heating degree days, base 65°F
Heat-pump hours, next 7 days
- h below 47°F
- 22
- h below 17°F
- 0
- h below 5°F
- 0
47, 17 and 5°F are the test points heat pumps are rated at. About 12 hours are near freezing and damp, when outdoor units defrost more often.
Comfort
Dry air outside (dew point 39°F).
Open the windows?
Sun, 1:00 PM–6:00 PM
Good stretch to open the windows.
Is this typical?
Washington Dulles International Airport · official normals 1991–2020 · records 1960–2026
Oct 24, today vs a typical year
Today’s expected high is 2°1° colder than typical.
- Normal high / low
- 65°18° / 42°6°
- Forecast high / low
- 63°17° / 38°3°
- Record high
- 84°29° in 2001
- Record low
- 15°−9° in 1969
Last 7 days vs normal
On average 2°1° colder than normal (daily mean temperature).
- −6°−3°SunOct 18
- −3°−2°MonOct 19
- +2°+1°TueOct 20
- ±0°WedOct 21
- −2°−1°ThuOct 22
- −1°FriOct 23
- —SatOct 24
Great Falls Crossing weather by month: normals, records, snow and freeze dates
Sun & moon
Sun
Sunrise 7:28 AM, sunset 6:18 PM.
- Daylight
- 10 h 50 min
- Losing 2 min 25 s a day; shortest Dec 21, 1 h 24 min less
- Golden hour
- 5:41–6:35 PM
- Morning 7:11–8:05 AM
- Blue hour
- 6:35–6:45 PM
- Morning 7:00–7:11 AM; first light 7:00 AM
Stars tonight? Fair
Mostly clear 6:45 PM–7 AM, but the moon is 99% lit and up.
Moon
Waxing gibbous
98% lit · growing
- Today
- sets 5:40 AM · rises 5:14 PM
- Full moon
- Oct 26
- New moon
- Nov 9
