The bar chart below shows the average monthly peak daytime temperatures at Herndon
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
°C | 4.7 | 6.6 | 12.5 | 18.3 | 23.4 | 28 | 30.5 | 29.5 | 25.9 | 19.8 | 13.7 | 7.3 |
°F | 40.5 | 43.9 | 54.5 | 64.9 | 74.1 | 82.5 | 86.8 | 85.1 | 78.7 | 67.6 | 56.7 | 45.1 |
Please note: these are the average peak daytime temperatures (usually around mid-afternoon) so do not show daytime / night highs and lows. To see the daily range of temperatures have a look at the temperature max / min chart below.
The graph below shows the average rainfall and number of rainy days per month.
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
mm | 69 | 69 | 86 | 79 | 98 | 87 | 91 | 99 | 89 | 80 | 86 | 84 |
inches | 2.7 | 2.7 | 3.4 | 3.1 | 3.9 | 3.4 | 3.6 | 3.9 | 3.5 | 3.1 | 3.4 | 3.3 |
Rainy days | 10 | 9 | 10 | 10 | 12 | 10 | 10 | 10 | 8 | 8 | 9 | 10 |
Average annual rainfall in Herndon: 978.7mm (385.3 inches)
The bar chart below shows the average daily sunshine hours in Herndon
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Hrs sunshine | 5.1 | 5.9 | 7.1 | 8.1 | 8.9 | 10 | 9.7 | 9.1 | 7.9 | 7 | 5.4 | 4.7 |
The graph below shows the daily range of temperatures for each month.
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Min °C | -5.6 | -4.3 | 0.4 | 5.2 | 10.7 | 15.7 | 18.5 | 17.6 | 13.6 | 6.5 | 1.8 | -3 |
Max °C | 5 | 6.9 | 12.8 | 18.6 | 23.7 | 28.4 | 30.8 | 29.8 | 26.3 | 20.1 | 14 | 7.6 |
Min °F | 22 | 24.3 | 32.7 | 41.4 | 51.3 | 60.2 | 65.2 | 63.7 | 56.4 | 43.7 | 35.2 | 26.7 |
Max °F | 31.5 | 34.3 | 43.9 | 53.4 | 63 | 71.6 | 76.3 | 74.7 | 67.8 | 55.9 | 46.2 | 36.1 |
The graph below shows the average sea temperature.
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
°C | 4.2 | 2.6 | 3.3 | 6.7 | 11.8 | 18.2 | 23.2 | 24.2 | 22.1 | 17.3 | 12.2 | 7.7 |
°F | 39.6 | 36.6 | 38 | 44.1 | 53.3 | 64.8 | 73.7 | 75.6 | 71.7 | 63.2 | 54 | 45.8 |
The graph below shows the average wind speed.
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
km/h | 15 | 16 | 16 | 16 | 14 | 13 | 12 | 11 | 12 | 13 | 14 | 14 |
mph | 9 | 10 | 10 | 10 | 9 | 8 | 7 | 7 | 7 | 8 | 9 | 9 |
A monthly average windspeed of over 16km/h or 10mph suggests a location is fairly windy.
The graph below shows the average relative humidity.
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
---|---|---|---|---|---|---|---|---|---|---|---|
67% | 65% | 63% | 62% | 69% | 71% | 72% | 74% | 74% | 72% | 69% | 69% |
Hottest month: | July | 30.5°C 86.9°F |
---|---|---|
Driest month: | January | 69mm 2.7ins |
Sunniest month: | June | 10hrs |
Coldest month: | January | 4.7°C 40.5°F |
Wettest month: | August | 99mm 3.9ins |
Warmest sea: | August | 24.2°C 75.6°F |