Herndon, United States — Weather in August 2026

Climate Overview

Herndon, United States in August has hot conditions, with highs reaching 29.4°C (85°F) and afternoons the warmest part of the day. Rain falls on about 13 days this month.

This month falls at the end of Summer.

Temperatures remain fairly steady throughout August, with daily highs around 29°C (84°F).

Rainfall is heaviest during the middle of the month, while the last third tends to be drier.

Expect around 11.0h of sunshine at the start of August, decreasing to 9.7h by the end.

The warmest days tend to fall around the 11th, averaging 30.4°C (87°F).

Compared to July, this month is about 2°C cooler with 1 fewer rainy days. Temperatures begin dropping heading into September.

Monthly August Averages

Temperature

29°C / 20°C

Feels Like

32°C / 23°C

Rain

13 days · 101 mm

Sunshine

10.5h / day

Humidity

74% — Muggy

Wind

11 km/h

Wind Direction

SW (221°)

Gusts

30 km/h

Daylight

13.6 h

Cloud Cover

57%

Clear Sky Days

2.8

UV Index

6.9 — High

Dew Point

20°C — Humid

Moon Phase

Waxing Crescent · 3%

Climate Charts

Daily averages based on historical data (2016–2025)

Daily Temperature

High Low

Daily Precipitation

Rainfall

Daily Sunshine

Sunshine

Daily Wind Speed

Wind Speed

Sun Position

Sunrise 06:23

Daylight 13.7h

Sunset 20:04

What to Expect

Daytime temperatures around 29°C (85°F) are ideal for full-day outdoor exploration. Keep afternoons flexible as tropical showers are common — they typically clear within an hour.

Rain most often builds later in the day, so mornings are typically the driest window and afternoon showers are more likely.

1 of the last 5 yearly records were warmer than this month's long-run average.

Compare Months

Month	Temp	Feels Like	Rain	Sun	Humidity	UV	Status	Details
January	6°C / -2°C	2°C / -6°C	9days (83 mm) Wet	6.2h Fair	68% Muggy	2.7 Moderate	Poor	View Details
February	9°C / 0°C	6°C / -4°C	10days (88 mm) Wet	6.7h Fair	67% Muggy	3.4 Moderate	Poor	View Details
March	14°C / 3°C	11°C / -1°C	10days (76 mm) Wet	8.3h Good	64% Muggy	5 Moderate	Fair	View Details
April best	19°C / 8°C	18°C / 5°C	10days (84 mm) Wet	9.1h Good	65% Muggy	5.9 High	Good	View Details
May best	23°C / 13°C	24°C / 12°C	14days (121 mm) Wet	9.2h Good	74% Muggy	6.5 High	Excellent	View Details
June best	28°C / 18°C	31°C / 19°C	11days (100 mm) Wet	11.3h Excellent	69% Muggy	7.3 Very High	Excellent	View Details
July	31°C / 22°C	35°C / 24°C	14days (129 mm) Wet	11.7h Excellent	70% Muggy	7.5 Very High	Fair	View Details
August best	29°C / 20°C	32°C / 23°C	13days (101 mm) Wet	10.5h Excellent	74% Muggy	6.9 High	Good	View Details
September best	26°C / 17°C	27°C / 18°C	11days (105 mm) Wet	8.5h Good	73% Muggy	5.2 High	Excellent	View Details
October	20°C / 11°C	19°C / 10°C	8days (73 mm) Wet	7.9h Good	72% Muggy	4.5 Moderate	Good	View Details
November	13°C / 4°C	11°C / 1°C	8days (73 mm) Wet	7.2h Good	67% Muggy	3.1 Moderate	Fair	View Details
December	8°C / 0°C	5°C / -4°C	9days (94 mm) Wet	5.9h Fair	70% Muggy	2.3 Moderate	Poor	View Details

What to Wear

Summer clothing like shorts, t-shirts, and sundresses will be comfortable. Bring a light cardigan for air-conditioned spaces.

A waterproof jacket or compact umbrella is recommended for occasional showers.

Packing List

UmbrellaWaterproof jacketBreathable clothingSunscreen (SPF 30+)Sun hatSunglassesComfortable walking shoes

Frequently Asked Questions

Expand all

Is August a good time to visit Herndon?

August is typically good for visiting Herndon, with average highs of 29°C (85°F) and around 13 rainy days. Herndon, United States in August has hot conditions, with highs reaching 29.4°C (85°F) and afternoons the warmest part o

Does it rain a lot in Herndon in August?

Herndon typically sees around 13 rainy days in August with 101 mm (4 in) of total rainfall. Pack a waterproof jacket.

Does it get cold at night in Herndon in August?

Nights stay pleasantly warm in Herndon during August, around 20°C (69°F). Light evening wear is sufficient.

What should I pack for Herndon in August?

With highs of 29°C (85°F) and lows of 20°C (69°F) in August, we recommend: Umbrella, Waterproof jacket, Breathable clothing, Sunscreen (SPF 30+), Sun hat. Comfortable walking shoes are essential.

Is August among the best months weather-wise in Herndon?

Yes, August offers some of the best weather conditions in Herndon with comfortable temperatures and lower chances of rain.

What is the UV index in Herndon in August?

The average UV index in Herndon during August is 7 (high). Wear sunscreen SPF 30+, a hat, and sunglasses. Limit direct sun exposure between 10 AM and 4 PM.

How many hours of daylight are there in Herndon in August?

Herndon gets approximately 14 hours of daylight per day in August, with around 11 hours of sunshine.

Does it snow in Herndon in August?

Snow is uncommon in Herndon during August based on 10-year climate averages.

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