Average annual temperature is 11.5 °C
Absolute maximum temperature: 37.1 °C
Absolute minimum temperature: -25.9 °C
Number of sunny days: 210 days
Number of rainy days: 136 days
Number of snow days: 19 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) | 12.3 | 13.3 | 23.8 | 27.5 | 30.8 | 32.6 | 34.9 | 37.1 | 35.1 | 32.2 | 18.6 | 14.7 |
| Average daytime temperature (°C) | 0.4 | 4.1 | 7.7 | 17.7 | 24.8 | 29.1 | 28.6 | 29.0 | 27.2 | 18.0 | 11.3 | 6.9 |
| Average temperature (°C) | -3.7 | -1.9 | 1.6 | 10.6 | 18.3 | 23.1 | 23.2 | 23.9 | 21.2 | 13.1 | 5.7 | 2.3 |
| Average night temperature (°C) | -6.8 | -6.4 | -2.7 | 5.0 | 12.2 | 17.2 | 18.1 | 19.4 | 16.1 | 9.0 | 1.2 | -0.9 |
| Absolute minimum temperature (°C) | -25.9 | -24.3 | -12.9 | -4.7 | 2.9 | 8.7 | 11.7 | 13.2 | 9.9 | -4.4 | -10.7 | -5.9 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight maximum duration (h) | 9.0 | 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) | 9.5 | 10.6 | 11.9 | 13.4 | 14.6 | 15.2 | 14.9 | 13.8 | 12.5 | 11.1 | 9.8 | 9.2 |
| Daylight minimum duration (h) | 9.0 | 10.0 | 11.0 | 12.0 | 14.0 | 15.0 | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 | 9.0 |
| Sunshine mean duration (h) | 4.6 | 7.1 | 7.8 | 9.7 | 11.3 | 12.4 | 12.1 | 11.5 | 10.3 | 7.8 | 7.2 | 4.7 |
| Precipitation (mm) | 48 | 49 | 44 | 45 | 76 | 76 | 90 | 67 | 37 | 47 | 6 | 48 |
| Sunny days | 17 | 17 | 16 | 17 | 18 | 14 | 15 | 15 | 18 | 16 | 24 | 23 |
| Rainy days | 6 | 8 | 12 | 12 | 13 | 16 | 16 | 16 | 12 | 14 | 4 | 7 |
| Snow days | 8 | 3 | 3 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 2 | 1 |
The best time to visit Herndon during the most sunny months:
The largest precipitation sum in Herndon is at