Herndon Weather in September

During September, Herndon experiences high daytime temperatures of 26°C (79°F) and cooler nights around 15°C (59°F). Expect quite a bit of rainfall. Around 102 mm (4 in) is typical.

Rainfall in Herndon in September

Typically, you can expect about 10 days of rain this month, with 102 mm (4 in) on average. When showers do arrive, they tend to be on the heavier side. Worth being prepared even if rain days are not that numerous.

Temperature in Herndon in September

Herndon in September gets highs of 26°C (79°F) during the day and drops to 15°C (59°F) at night. Conditions stay fairly consistent through the month, making it easier to plan what to wear. Nights cool down to 15°C (59°F), so a light jacket or extra layer is useful once the sun goes down. On the plus side, the cooler nights make for comfortable sleeping conditions.

Sunshine in Herndon in September

The city usually sees around 225 hours of sunlight, indicating many sunny days — a great month for sightseeing.

Our weather planner can help you find worldwide destinations with pleasant weather during this period. April, May, June, September and October typically offer the best weather for Herndon.

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Check the conditions for any month of the year.

• January
• February
• March
• April

• May
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• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our Herndon's climate page.

Herndon Temperature in September

Min Temperature 15°C (59°F)  

Max Temperature 26°C (79°F)  

Chance of Rain 33%  

Precipitation 102 mm (4 in)  

Rainy days 10 days  

Humidity 68% *  

Sunshine 225 hours *  

Percentage Sunshine 60% *  

* Data from: Washington DC, the United States of America (33 KM, 20 Miles).

What to Wear in Herndon in September

Warm but pleasant conditions in Herndon in September. Focus on lightweight, maybe with natural fabrics, cotton blend shirts, comfortable shorts, and breathable footwear. A light cover-up for sun protection is smart too. Expect heavy rainfall, so bring good rain protection and waterproof bags. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.

What To Do in Herndon in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

9/10

Cycling

7/10

Walking

7/10

Camping

6/10

Outdoor sports

7/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our Herndon's climate page.

More climate data for Herndon

Temperature Rainfall Sunshine Humidity

See the full Herndon climate overview or explore weather in the United States of America.