Herndon Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Herndon.
Climate overview of Herndon
The climate in Herndon, Virginia, United States of America, is marked by large temperature swings across the seasons, ranging from 31°C (88°F) in July to 6°C (43°F) in January.
The city receives considerable rain/snowfall, with around 1116 mm (44 in) annually. October is the wettest month. It has very warm summers and cold winters. June is the sunniest month, averaging 9.4 hours of sunshine per day.
Herndon Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Herndon - and find the best time to visit.
Monthly Temperature in Herndon
In Herndon, temperatures differ significantly between summer and winter months. Typically, average maximum daytime temperatures range from a very warm 31°C (88°F) in July to a chilly 6°C (43°F) in the coolest month, January.
Nights vary from 20°C (68°F) in July to around -4°C (25°F) during the colder months.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Herndon
Herndon experiences significant rain/snowfall throughout the year, averaging 1116 mm (44 in) of precipitation annually. Herndon offers a pleasant mix of wetter and slightly drier months. The difference in precipitation between the wettest month October (134 mm (5.3 in)) and the driest month February (63 mm (2.5 in)) is not too significant. For more details, please visit our Herndon Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Herndon
For those who appreciate different seasons, Herndon serves as an ideal destination. Expect longer, more sun-filled days in June with an average of 9.4 hours of sunshine daily, and embrace the darker days in December, offering only 4.3 hours of daily sunlight.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Humidity in Herndon by Month
The relative humidity is high throughout the year in Herndon.
The city experiences its highest humidity in August, reaching 69%. In March, the humidity drops to its lowest level at 58%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Best Time to Visit Herndon
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: April, May, June, September and October
- Warmest weather: July and August
- Most sunshine: June and July
- Seasonal pattern: Very warm summers and cold winters
- Coldest conditions: January, with freezing nights around -4°C (25°F).
Frequently asked questions about the climate in Herndon
What is the best time to visit Herndon?
April, May, June, September and October typically offer the most optimal weather in Herndon. In contrast, January, February and December tend to have less optimal conditions. Herndon has very warm summers and cold winters.
What temperatures can I expect in Herndon?
Daytime highs range from 6°C (43°F) in January to 31°C (88°F) in July. Nighttime lows range from -4°C (25°F) to 20°C (68°F). Temperatures vary considerably through the year.
How much rain does Herndon get?
Annual rainfall is around 1116 mm (44 in). October is the wettest month with 134 mm (5.3 in), while February is the driest with 63 mm (2.5 in).
How sunny is Herndon?
Herndon receives around 2,520 hours of sunshine per year. June is the sunniest month with 282 hours, while December is the cloudiest with just 130 hours. Overall, Herndon enjoys abundant sunshine.
Herndon 3-Day Forecast
Herndon 3-Day Forecast
Herndon on the map
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