Herndon (VA)
September
Weather in Herndon, Virginia for September 2026
Your guide to Herndon weather in September - trends and predictions
So far, September 2026 in Herndon shows a warmer trend than usual by 2.1 °F.
Expect cooler weather in the next days in Herndon with the forecast suggesting a temperature of 26.7 °F, lower than the historical average.
In general, the average temperature in Herndon at the beginning of September is 30.9 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 26 °F by the end of September.
The climate of Herndon in September is notably wet, with an average of 11 rainy days, and a total of 295.2 mm of precipitation.
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Temperatures
Rain 🌧️
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19
Dry days
11
Rainy days
0
Snow days
26°/17°
Temperatures
13 km/h
Avg max wind
67 %
Avg humidity
Herndon Weather September
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Temperatures trend during September in Herndon
See the weather trend as well as the moving average line
September weather in Herndon day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Cloudy | 32° /18° | 0 mm | 9 | |
| Sept. 2 | Cloudy | 31° /19° | 3 mm | 8 | |
| Sept. 3 |  Partly cloudy | 31° /19° | 0 mm | 9 | |
| Sept. 4 | Cloudy | 34° /19° | 8.5 mm | 9 | |
| Sept. 5 | Cloudy | 31° /19° | 1.7 mm | 7 | |
| Sept. 6 |  Moderate or heavy rain shower | 30° /19° | 55 mm | 8 | |
| Sept. 7 |  Overcast | 27° /15° | 0 mm | 6 | |
| Sept. 8 |  Sunny | 28° /12° | 0 mm | 8 | |
| Sept. 9 | Partly cloudy | 28° /15° | 0 mm | 6 | |
| Sept. 10 | Overcast | 27° /18° | 1.6 mm | 4 | |
| Sept. 11 | Cloudy | 26° /18° | 0.2 mm | 5 | |
| Sept. 12 | Partly cloudy | 29° /17° | 1.6 mm | 5 | |
| Sept. 13 | Partly cloudy | 29° /19° | 1.6 mm | 5 | |
| Sept. 14 | Cloudy | 28° /18° | 0 mm | 7 | |
| Sept. 15 | Overcast | 27° /16° | 0.8 mm | 7 | |
| Sept. 16 | Sunny | 29° /15° | 0 mm | 6.9 | |
| Sept. 17 | Sunny | 31° /18° | 6.5 mm | 7.2 | |
| Sept. 18 | Overcast | 28° /22° | 1.8 mm | 6.1 | |
| Sept. 19 | Overcast | 25° /20° | 0 mm | 6.7 | |
| Sept. 20 |  Light rain shower | 28° /19° | 2.5 mm | 6 | |
| Sept. 21 | Patchy rain possible | 23° /20° | 0.7 mm | 5 | |
| Sept. 22 | Light rain shower | 25° /21° | 19.9 mm | 6 | |
| Sept. 23 | Light rain shower | 28° /20° | 9.7 mm | 6 | |
| Sept. 24 | Partly cloudy | 28° /18° | 0.4 mm | 7 | |
| Sept. 25 | Sunny | 21° /14° | 0.8 mm | 5 | |
| Sept. 26 | Sunny | 25° /15° | 0 mm | 6 | |
| Sept. 27 | Sunny | 26° /15° | 0 mm | 7 | |
| Sept. 28 | Overcast | 27° /17° | 0 mm | 7 | |
| Sept. 29 | Sunny | 30° /17° | 0 mm | 7 | |
| Sept. 30 | Overcast | 25° /18° | 0 mm | 1 | |
| Next | |||||
Important Notice
Our weather forecast for Herndon in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Herndon forecast closer to your planned date for the most up-to-date weather information.
Change Month
Herndon in September - FAQ
What are the expected maximum and minimum temperatures in Herndon during September?
During September, expect a variety of temperatures with highs around 26° and lows near 17°, suitable for diverse activities and preferences.
How much rainfall should be expected in Herndon during September?
Significant rainfall exceeding 295.2 mm is expected in Herndon during September, occurring over more than 11 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Herndon during September?
The average wind speed in Herndon during September is 13 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Herndon
Explore the daily rainfall trends and prepare for Herndons September weather 💧
Typically, Herndon has 11 rainy days in September with a total of 295.2 mm of rainfall.
UV exposure in Herndon during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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