Frost Advisory
Starts in 9 h 50 min
When
From 1 AM to 9 AM EDT Sunday.
Where
Portions of central, northeast, and northern Maryland and northern Virginia.
Issued for this forecast zone · National Weather Service Baltimore MD/Washington DC
What, impacts and precautionsHide details
What
Temperatures as low as 33 will result in frost formation.
Impacts
Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered.
Precautionary actions
Take steps now to protect tender plants from the cold.
Areas: Frederick; Carroll; Northern Baltimore; Cecil; Northwest Montgomery; Northwest Howard; Northwest Harford; Southeast Harford; Rappahannock; Culpeper; Northern Fauquier; Southern Fauquier; Western Loudoun; Eastern Loudoun; Northwest Prince William; Central and Southeast Prince William/Manassas/Manassas Park
See it on weather.gov (opens in a new tab)

Observed 2:50 PM EDT at KHEF

Loch Lomond, VA weather

Mostly sunny and 63°17°, jacket by 7 PM.

Mostly agree

Now 63°17°

Mostly sunny

Wind: Calm; Up to 5 mph8 km/h through 3 AM
Dew point: 41°5°; Comfortable
UV index: 4Moderate; Moderate until 5 PM
Air quality: 30Good; Ozone · tomorrow moderate
Pressure: 30.51 inHg1033 hPa; Falling · −0.06 inHg−2.0 hPa in 3 h

No precipitation expected in the next 2 hours.

From forecast models

Next 48 hours

Good hours for

Below 50°10° tonight after 9 PM
Fog tonight 2–3 AM
Fog tomorrow 8–9 AM
Above 50°10° tomorrow by 11 AM
Fog Monday 7–9 AM

This afternoonNear 64°18° · Clear
TonightDown to 37°3° by 5 AM · Partly cloudy
Tomorrow morningUp to 54°12° by 11 AM · Clear
Tomorrow afternoonUp to 66°19° by 4 PM · Clear
Tomorrow nightDown to 38°3° by 4 AM · Clear
Monday morningUp to 57°14° by 11 AM · Partly cloudy
Monday afternoonUp to 69°21° by 2 PM · Clear

Hourly forecast, next 48 hours, in the place's local time
Hour	Conditions	Temperature	Feels like	Precipitation	Wind	Humidity	Cloud cover	UV index
Sat 3p	Partly sunny	63°17° (likely 61°16° to 64°18°)	63°17°	0%	5 mph8 km/h from SE, gusts 8 mph13 km/h	44%	17%	4
Sat 4p	Partly sunny	63°17° (likely 61°16° to 64°18°)	63°17°	0%	5 mph8 km/h from SE, gusts 8 mph13 km/h	44%	20%	3
Sat 5p	Partly sunny	64°18° (likely 60°16° to 64°18°)	64°18°	0%	5 mph8 km/h from SE, gusts 8 mph12 km/h	43%	21%	2
Sat 6p	Clear	60°16° (likely 57°14° to 60°16°)	60°16°	0%	3 mph5 km/h from SE, gusts 9 mph15 km/h	49%	18%	0
Sat 7p	Clear	55°13° (likely 53°12° to 55°13°)	55°13°	0%	3 mph5 km/h from E, gusts 6 mph10 km/h	61%	20%	0
Sat 8p	Clear	52°11° (likely 51°11° to 53°12°)	52°11°	0%	3 mph5 km/h from E, gusts 7 mph11 km/h	71%	16%	0
Sat 9p	Clear	47°8° (likely 47°8° to 51°11°)	47°8°	0%	2 mph3 km/h from E, gusts 6 mph10 km/h	86%	13%	0
Sat 10p	Clear	44°7° (likely 44°7° to 49°9°)	44°7°	0%	1 mph2 km/h from E, gusts 6 mph10 km/h	96%	16%	0
Sat 11p	Mostly clear	44°7° (likely 44°7° to 48°9°)	44°7°	0%	1 mph2 km/h from E, gusts 7 mph11 km/h	96%	31%	0
Sun 12a	Partly cloudy	41°5° (likely 41°5° to 48°9°)	41°5°	0%	0 mph0 km/h, gusts 5 mph7 km/h	100%	50%	0
Sun 1a	Cloudy	41°5° (likely 41°5° to 49°9°)	41°5°	0%	0 mph0 km/h, gusts 5 mph8 km/h	100%	53%	0
Sun 2a	Fog	40°4° (likely 40°4° to 47°8°)	40°4°	0%	0 mph0 km/h, gusts 5 mph8 km/h	100%	39%	0
Sun 3a	Clear	39°4° (likely 39°4° to 46°8°)	39°4°	0%	0 mph0 km/h, gusts 3 mph4 km/h	100%	20%	0
Sun 4a	Clear	38°3° (likely 38°3° to 46°8°)	38°3°	0%	0 mph0 km/h, gusts 3 mph5 km/h	100%	18%	0
Sun 5a	Clear	37°3° (likely 37°3° to 44°7°)	37°3°	0%	1 mph2 km/h from N, gusts 4 mph7 km/h	100%	18%	0
Sun 6a	Clear	36°2° (likely 36°2° to 43°6°)	36°2°	0%	0 mph0 km/h, gusts 5 mph8 km/h	100%	16%	0
Sun 7a	Sunny	36°2° (likely 36°2° to 42°6°)	36°2°	0%	0 mph0 km/h, gusts 6 mph9 km/h	100%	18%	0
Sun 8a	Fog	37°3° (likely 37°3° to 42°6°)	37°3°	0%	1 mph2 km/h from N, gusts 5 mph9 km/h	100%	32%	0
Sun 9a	Mostly sunny	41°5° (likely 41°5° to 47°8°)	41°5°	0%	1 mph2 km/h from N, gusts 4 mph7 km/h	100%	51%	1
Sun 10a	Mostly sunny	49°9° (likely 49°9° to 53°12°)	49°9°	0%	1 mph2 km/h from N, gusts 7 mph11 km/h	83%	21%	2
Sun 11a	Mostly sunny	54°12° (likely 54°12° to 58°14°)	54°12°	0%	1 mph2 km/h from N, gusts 6 mph9 km/h	74%	10%	3
Sun 12p	Mostly sunny	59°15° (likely 59°15° to 62°17°)	59°15°	0%	1 mph2 km/h from E, gusts 6 mph9 km/h	60%	12%	4
Sun 1p	Mostly sunny	62°17° (likely 62°17° to 64°18°)	62°17°	0%	1 mph2 km/h from E, gusts 5 mph8 km/h	54%	21%	4
Sun 2p	Mostly sunny	64°18° (likely 64°18° to 66°19°)	64°18°	0%	1 mph2 km/h from SE, gusts 5 mph9 km/h	50%	16%	4
Sun 3p	Mostly sunny	65°18° (likely 64°18° to 66°19°)	65°18°	0%	1 mph2 km/h from SE, gusts 5 mph8 km/h	48%	14%	4
Sun 4p	Sunny	66°19° (likely 64°18° to 67°19°)	66°19°	0%	1 mph2 km/h from SE, gusts 7 mph11 km/h	47%	16%	3
Sun 5p	Sunny	65°18° (likely 63°17° to 66°19°)	65°18°	0%	1 mph2 km/h from SE, gusts 6 mph9 km/h	48%	9%	1
Sun 6p	Clear	62°17° (likely 59°15° to 62°17°)	62°17°	0%	1 mph2 km/h from SE, gusts 5 mph8 km/h	54%	3%	0
Sun 7p	Clear	57°14° (likely 55°13° to 58°14°)	57°14°	0%	1 mph2 km/h from E, gusts 5 mph8 km/h	67%	2%	0
Sun 8p	Clear	51°11° (likely 51°11° to 56°13°)	51°11°	0%	1 mph2 km/h from E, gusts 4 mph7 km/h	83%	0%	0
Sun 9p	Clear	48°9° (likely 48°9° to 53°12°)	48°9°	0%	0 mph0 km/h, gusts 5 mph9 km/h	89%	0%	0
Sun 10p	Clear	46°8° (likely 46°8° to 50°10°)	46°8°	0%	0 mph0 km/h, gusts 4 mph7 km/h	96%	0%	0
Sun 11p	Clear	44°7° (likely 44°7° to 49°9°)	44°7°	0%	0 mph0 km/h, gusts 3 mph4 km/h	100%	1%	0
Mon 12a	Clear	43°6° (likely 43°6° to 47°8°)	43°6°	0%	0 mph0 km/h, gusts 3 mph4 km/h	100%	1%	0
Mon 1a	Clear	42°6° (likely 42°6° to 46°8°)	42°6°	0%	0 mph0 km/h, gusts 2 mph4 km/h	100%	0%	0
Mon 2a	Clear	40°4° (likely 40°4° to 45°7°)	40°4°	0%	0 mph0 km/h, gusts 3 mph5 km/h	100%	2%	0
Mon 3a	Clear	40°4° (likely 40°4° to 44°7°)	40°4°	0%	0 mph0 km/h, gusts 3 mph5 km/h	100%	15%	0
Mon 4a	Mostly clear	38°3° (likely 38°3° to 44°7°)	38°3°	0%	1 mph2 km/h from W, gusts 3 mph5 km/h	100%	21%	0
Mon 5a	Mostly clear	38°3° (likely 38°3° to 43°6°)	38°3°	0%	1 mph2 km/h from W, gusts 3 mph5 km/h	100%	23%	0
Mon 6a	Mostly clear	37°3° (likely 37°3° to 42°6°)	37°3°	0%	1 mph2 km/h from W, gusts 3 mph6 km/h	100%	38%	0
Mon 7a	Fog	36°2° (likely 36°2° to 42°6°)	36°2°	0%	1 mph2 km/h from NW, gusts 3 mph6 km/h	100%	50%	0
Mon 8a	Fog	37°3° (likely 36°2° to 44°7°)	37°3°	0%	1 mph2 km/h from NW, gusts 3 mph5 km/h	100%	45%	0
Mon 9a	Sunny	42°6° (likely 38°3° to 51°11°)	42°6°	0%	1 mph2 km/h from NW, gusts 3 mph5 km/h	96%	25%	1
Mon 10a	Mostly sunny	49°9° (likely 47°8° to 56°13°)	49°9°	0%	1 mph2 km/h from NW, gusts 4 mph6 km/h	83%	4%	2
Mon 11a	Sunny	57°14° (likely 55°13° to 60°16°)	57°14°	0%	2 mph3 km/h from NW, gusts 5 mph8 km/h	67%	0%	3
Mon 12p	Mostly sunny	62°17° (likely 62°17° to 64°18°)	62°17°	0%	2 mph3 km/h from NW, gusts 6 mph9 km/h	56%	3%	4
Mon 1p	Sunny	66°19° (likely 66°19° to 68°20°)	66°19°	0%	3 mph5 km/h from NW, gusts 10 mph16 km/h	48%	0%	4
Mon 2p	Sunny	69°21° (likely 67°19° to 69°21°)	69°21°	0%	3 mph5 km/h from NW, gusts 11 mph17 km/h	44%	0%	4

Days ahead

Shaded: typical range for these dates (1991–2020)

Today, Oct 24. Partly sunny. High 64°18°, low 36°2°. Typical 65°18° / 42°6°. Dry. Mostly agree.
1. Afternoon
  noon–6 PM
  Partly sunny, 64°18°
  Dry
2. Evening
  6 PM–midnight
  Clear, 52°11°
  Dry
3. Overnight
  midnight–6 AM
  Clear, 37°3°
  Dry
Official NWS forecast
Today: Mostly sunny, with a high near 64. Southeast wind around 5 mph.
Tonight: Patchy fog between 2am and 5am, then patchy frost and patchy fog. Mostly clear, with a low around 36. East wind 0 to 3 mph.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
61°16°–64°18°
Low, likely
35°2°–38°3°
Typical high / low
65°18° / 42°6°
Wind
6 mph9 km/h, gusts 12 mph19 km/h
UV peak
4
Tomorrow, Oct 25. Cloudy. High 66°19°, low 36°2°. Typical 64°18° / 42°6°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Mostly sunny, 37°3°
  Dry
2. Afternoon
  noon–6 PM
  Mostly sunny, 66°19°
  Dry
3. Evening
  6 PM–midnight
  Clear, 51°11°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 38°3°
  Dry
Official NWS forecast
Day: Patchy frost and patchy fog before 9am. Sunny, with a high near 66. Northeast wind around 1 mph.
Night: Clear, with a low around 36. Northeast wind around 1 mph.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
64°18°–67°19°
Low, likely
36°2°–42°6°
Typical high / low
64°18° / 42°6°
Wind
6 mph9 km/h
UV peak
4
Monday, Oct 26. Mostly sunny. High 71°22°, low 47°8°. Typical 64°18° / 41°5°. Dry. Forecasts agree.
1. Morning
  6 AM–noon
  Sunny, 37°3°
  Dry
2. Afternoon
  noon–6 PM
  Sunny, 69°21°
  Dry
3. Evening
  6 PM–midnight
  Clear, 55°13°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 49°9°
  Dry
Official NWS forecast
Day: Patchy frost before 9am. Sunny, with a high near 71. Northwest wind around 3 mph.
Night: Mostly clear, with a low around 47.
Forecasts agreeIndependent forecasts are close; the range is narrow.
High, likely
68°20°–71°22°
Low, likely
36°2°–47°8°
Typical high / low
64°18° / 41°5°
Wind
7 mph11 km/h, gusts 13 mph22 km/h
UV peak
4
Tuesday, Oct 27. Mostly sunny. High 70°21°, low 46°8°. Typical 64°18° / 41°5°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Sunny, 48°9°
  Dry
2. Afternoon
  noon–6 PM
  Sunny, 67°20°
  Dry
3. Evening
  6 PM–midnight
  Clear, 57°14°
  Dry
4. 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 70.
Night: Mostly clear, with a low around 46.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
65°18°–70°21°
Low, likely
44°7°–51°11°
Typical high / low
64°18° / 41°5°
Wind
8 mph12 km/h, gusts 17 mph27 km/h
UV peak
4
Wednesday, Oct 28. Cloudy. High 67°19°, low 47°8°. Typical 64°18° / 41°5°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Cloudy, 47°8°
  Dry
2. Afternoon
  noon–6 PM
  Cloudy, 65°18°
  Dry
3. Evening
  6 PM–midnight
  Cloudy, 56°13°
  Dry
4. Overnight
  midnight–6 AM
  Cloudy, 48°9°
  Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Partly sunny, with a high near 67.
Night: Mostly cloudy, with a low around 47.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
63°17°–67°19°
Low, likely
43°6°–48°9°
Typical high / low
64°18° / 41°5°
Wind
6 mph10 km/h, gusts 15 mph24 km/h
UV peak
4
Thursday, Oct 29. Cloudy. High 72°22°, low 48°9°. Typical 63°17° / 40°4°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Partly sunny, 47°8°
  Dry
2. Afternoon
  noon–6 PM
  Mostly sunny, 68°20°
  Dry
3. Evening
  6 PM–midnight
  Clear, 57°14°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 48°9°
  Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Mostly sunny, with a high near 72.
Night: Mostly clear, with a low around 48.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
67°19°–72°22°
Low, likely
45°7°–48°9°
Typical high / low
63°17° / 40°4°
Wind
8 mph12 km/h, gusts 23 mph37 km/h
UV peak
4
Friday, Oct 30. Mostly sunny. High 75°24°, low 50°10°. Typical 63°17° / 40°4°. Dry. Forecasts agree.
1. Morning
  6 AM–noon
  Sunny, 48°9°
  Dry
2. Afternoon
  noon–6 PM
  Sunny, 75°24°
  Dry
3. Evening
  6 PM–midnight
  Clear, 61°16°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 50°10°
  Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Sunny, with a high near 75.
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
6 mph10 km/h, gusts 26 mph42 km/h
UV peak
4
Saturday, Oct 31. Cloudy. High 72°22°, low 49°9°. Typical 62°17° / 40°4°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Mostly sunny, 48°9°
  Dry
2. Afternoon
  noon–6 PM
  Cloudy, 74°23°
  Dry
3. Evening
  6 PM–midnight
  Cloudy, 61°16°
  Dry
4. Overnight
  midnight–6 AM
  Cloudy, 57°14°
  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.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
70°21°–75°24°
Low, likely
45°7°–54°12°
Typical high / low
62°17° / 40°4°
Wind
6 mph10 km/h, gusts 27 mph44 km/h
UV peak
4
Sunday, Nov 1. Drizzle. High 70°21°, low 55°13°. Typical 62°17° / 40°4°. Rain 0.03 in0.8 mm, 30% chance. Forecasts differ.
1. Morning
  6 AM–noon
  Cloudy, 58°14°
  Dry
2. Afternoon
  noon–6 PM
  Drizzle, 69°21°
  30% chance · 0.01 in0.3 mm
3. Evening
  6 PM–midnight
  Drizzle, 65°18°
  30% chance · 0.01 in0.3 mm
4. Overnight
  midnight–6 AM
  Drizzle, 63°17°
  20% chance · 0.04 in1 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°–73°23°
Low, likely
53°12°–57°14°
Typical high / low
62°17° / 40°4°
Wind
10 mph16 km/h, gusts 24 mph38 km/h
UV peak
2
Monday, Nov 2. Drizzle. High 73°23°, low 59°15°. Typical 62°17° / 39°4°. Rain 0.48 in12 mm, 30% chance. Forecasts differ.
1. Morning
  6 AM–noon
  Drizzle, 64°18°
  20% chance · 0.02 in0.5 mm
2. Afternoon
  noon–6 PM
  Drizzle, 73°23°
  Dry
3. Evening
  6 PM–midnight
  Drizzle, 65°18°
  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
64°18°–79°26°
Low, likely
51°11°–66°19°
Typical high / low
62°17° / 39°4°
Wind
17 mph27 km/h, gusts 37 mph60 km/h

10 days15 days30 days

The outlook

Today
Dry, high 64°, low 36°.
Tomorrow
Dry, high 66°, low 36°.
Monday
Dry, high 71°, low 47°, warming up.
Rest of week
Mostly dry, highs 67–75°.

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

Full-screen radar

Rivers

NOAA river gauges within 25 mi

Flat Branch near Unnamed Tributary At Amherst Drive

0.7 mi

Level: 20.5 ft

Reading from Sat 2:05 PM · NWS gauge page

Flat Branch at Ben Lomond Park

0.8 mi

Level: 0.7 ft

Reading from Sat 12:55 PM · NWS gauge page

Buckhall Branch at Signal Hill Road

3.5 mi

Level: 0.6 ft

Reading from Sat 1:40 PM · NWS gauge page

Youngs Branch at Manassas Battlefield

3.5 mi

Below flood stage

Level: 0.6 ft

Reading from Sat 1:40 PM · NWS gauge page

For your home

What this week’s weather means for heating, cooling, pipes and fresh air.

Heating this week

About 64% less heating than a typical week.

This week 32Typical 88

Heating degree days, base 65°F

Heat-pump hours, next 7 days

h below 47°F: 25
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 19 hours are near freezing and damp, when outdoor units defrost more often.

Comfort

Dry air outside (dew point 41°F).

Open the windows?

Today, 4:00 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 about typical for the date.

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

Loch Lomond weather by month: normals, records, snow and freeze dates

Sun & moon

Sun

Daylight: 10 h 51 min; Losing 2 min 21 s a day; shortest Dec 21, 1 h 24 min less
Golden hour: 5:42–6:35 PM; Morning 7:11–8:05 AM
Blue hour: 6:35–6:46 PM; Morning 7:01–7:11 AM; first light 7:01 AM

Stars tonight? Fair

Mostly clear 6:46–11 PM, but the moon is 99% lit and up.

Moon

Waxing gibbous

97% lit · growing

Today: sets 5:41 AM · rises 5:15 PM
Full moon: Oct 26
New moon: Nov 9

Looking west from Loch Lomond. The highest point on the skyline is about 3,900 ft, 52 mi away.Skyline from USGS elevation data, heights drawn up to 6× taller. Sky, sun and moon as they are now.

1 active weather alert

Frost Advisory