Average annual temperature is 12.5 °C
Absolute maximum temperature: 34.5 °C
Absolute minimum temperature: -11.5 °C
Number of sunny days: 165 days
Number of rainy days: 194 days
Number of snow days: 6 days
Look at detailed online map of Herndon
* Weather data for Herndon United States is based on climate observations for 2026 year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Absolute maximum temperature (°C) | 16.3 | 19.1 | 18.8 | 31.2 | 32.1 | 34.5 | 34.5 | 31.8 | 33.2 | 27.3 | 20.5 | 15.0 |
| Average daytime temperature (°C) | 7.4 | 9.3 | 10.1 | 19.6 | 22.9 | 26.4 | 30.0 | 27.9 | 24.2 | 18.6 | 10.7 | 8.1 |
| Average temperature (°C) | 3.7 | 3.3 | 4.5 | 12.8 | 15.7 | 20.2 | 24.3 | 22.4 | 19.0 | 13.7 | 5.7 | 4.3 |
| Average night temperature (°C) | 0.9 | -1.1 | 0.1 | 6.9 | 8.7 | 14.6 | 19.5 | 17.9 | 14.8 | 9.8 | 2.0 | 1.2 |
| Absolute minimum temperature (°C) | -4.7 | -11.5 | -5.9 | 0.0 | 3.5 | 9.3 | 15.8 | 14.7 | 9.3 | 2.6 | -5.2 | -3.3 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight maximum duration (h) | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 15.0 | 15.0 | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 |
| Daylight mean duration (h) | 9.6 | 10.7 | 11.9 | 13.3 | 14.5 | 15.0 | 14.8 | 13.8 | 12.5 | 11.1 | 9.9 | 9.3 |
| Daylight minimum duration (h) | 9.0 | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 | 9.0 |
| Sunshine mean duration (h) | 4.6 | 6.8 | 7.1 | 9.1 | 11.6 | 11.0 | 12.2 | 10.7 | 8.9 | 7.8 | 7.3 | 4.3 |
| Precipitation (mm) | 94 | 38 | 88 | 111 | 20 | 90 | 124 | 123 | 132 | 70 | 51 | 109 |
| Sunny days | 9 | 15 | 12 | 15 | 20 | 11 | 8 | 9 | 16 | 18 | 18 | 14 |
| Rainy days | 20 | 12 | 19 | 15 | 11 | 19 | 23 | 22 | 14 | 13 | 11 | 15 |
| Snow days | 2 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 2 |
The best time to visit Herndon during the most sunny months:
The largest precipitation sum in Herndon is at