Climate and monthly weather forecastHerndon, VA
Climate and monthly weather forecast
The climate of Herndon
Herndon, Virginia, found within the United States, rests under the Köppen climate classification of Cfa, synonymous with a Humid subtropical, no dry season. Alongside its geographical segmentation, Herndon experiences a wide disparity in weather conditions aided by subtle shifts between seasons.All year round, average temperatures occupy the spectrum of 25.9°F (-3.4°C), considered low in January, gradually escalating to peaks of 87.8°F (31°C) in July. Facing no singular dry season, rainfall regularly appears throughout twelve months, the minimum recorded being 1.93" (49mm) in September, making a steady climb to reach a maximum of 3.78" (96mm) by August. In reverse, day to day sunshine varies less dramatically from 5 hours/day in December and January to 10.7 hours/day in July, while UV index hits its apex level of 6 noticeably over the sunnier months of May to September.
Particularly noticeable is the presence and subsequent disappearance of snowfall over the year. Accumulation starts to manifest in December with 0.12" (3mm), peaks in January with 3.54" (90mm), and diminishes rapidly to nothing by April, remaining absent until its minor resurgence towards the year's end.
The best time to visit Herndon
For those who appreciate milder weather complemented by longer daylight hours, the optimum period to visit Herndon would be from May to September. Average high temperatures range from 75°F (23.9°C) to 87.8°F (31°C) during these months, while the relative humidity hovers around 72-76%. Days are longer with between 13.6 to 14.9 hours of daylight, with sunlight adorning about 50% of those hours. Precipitation is relatively high compared to most of the months, but between 14.8 and 17.5 days are cohabited by rainfall, ensuring a fair portion of dry days.The worst time to visit Herndon
Given the inclement weather conditions, December through February poses a less desirable period to visit Herndon. Average high temperatures drop significantly, fluctuating between 39.7°F (4.3°C) and 45.1°F (7.3°C), while low temperatures hover around the freezing point from 25.9°F (-3.4°C) to 32°F (0°C) during this period. Furthermore, limited daylight hours (from 9.5 to 10.8 hours per day) and relatively high cloud cover at between 46 to 47% significantly reduce overall sunshine that reaches a minimum of 5 hours a day.Spring weather in Herndon
Herndon transitions into spring with temperatures warming from an average high of 52.5°F (11.4°C) in March to 64.9°F (18.3°C) in April. With daylight hours ranging from 12 to 13.3, an increase in sunshine hours from 6.6 to 8.7 further imbues the season with more warmth. Notably, rainfall figures also edge up from 2.44" (62mm) in March to 2.8" (71mm) in April, with roughly half of the month experiencing rainfall.Summer weather in Herndon
Typically, the season of summer in Herndon is characterized by temperatures from 75°F (23.9°C) to 87.8°F (31°C) and relative humidity hovering around 70 to 76%. Despite this, it is underscored by an increase in daily sunshine hours to a yearly high of 10.7 in July. Rainfall figures further peak within this season, with 2.48" (63mm) in June and rising to 3.78" (96mm) by August.Autumn weather in Herndon
Autumn in Herndon greets inhabitants with cooling temperatures from 78.3°F (25.7°C) in September down to 53.6°F (12°C) by November. Interestingly, the downward shift contrasts with the amount of rainfall tapering off significantly, decreasing from 1.93" (49mm) in September to 2.36" (60mm) in November. Sunshine hours also understandably lessen, ranging from 8.7 to 5.6, with daylight hours shortening from 12.4 to 10.1 during this period.Winter weather in Herndon
Winters in Herndon are characteristically unsettled, with lower average temperatures between 39.7°F (4.3°C) and 45.1°F (7.3°C) from December to February, plunging further at night, hovering around the freezing mark. Rainfall levels rise from 2.36" (60mm) recorded in November to peak at 2.68" (68mm) in December, and steadily decreasing thereafter. Snowfall accentuates this, with highest accumulation seen in January at 3.54" (90mm). As expected, daylight hours decrease to a yearly low of 9.5 hours in December, while sunshine hours remain steady at 5 hours per day, briefly peaking at 5.6 hours in February. This, in combination with relative humidity reaching its yearly high of 78%, embraces the traditional vision of winter in Herndon.Weather in January
The weather in January in Herndon, Virginia takes on the true essence of winter, with conditions staying relatively cold throughout the month. This month is characterized by an average high temperature of 39.7°F (4.3°C) and a low of 25.9°F (-3.4°C), so it's advisable to bundle up when heading outdoors. Weather in January »Weather in February
As winter slowly loosens its grip on Herndon, February weather sees a subtle upward shift in temperatures. However, the average high temperature peaks at 43.9°F (6.6°C), making it still a relatively chilly time of year. This month stands out as one of the year's snowiest periods, with snowflakes decorating the city's landscapes. Weather in February »Weather in March
With spring in sight, March in Herndon comes with a noticeable rise in temperature. The month witnesses average high and low temperatures reaching 52.5°F (11.4°C) and 35.6°F (2°C) respectively, offering a relief from the spine-chilling winter freeze. Weather in March »Weather in April
A noticeable shift in weather conditions becomes apparent in April, with warmer temperatures and rising humidity levels taking over Herndon. The highlight of April's weather would have to be the significant increase in temperature, with the average high soaring to 64.9°F (18.3°C), and the low resting at 45.7°F (7.6°C). Weather in April »Weather in May
As Herndon transitions into summer, May ushers in even warmer weather. This is when thermometers touch an inviting high of around 75°F (23.9°C) and a balmy low of about 55°F (12.8°C). May typically sees increased rainfall levels, making umbrellas a common sight. Weather in May »Weather in June
June marks the onset of summer in Herndon, which translates into warm sunshine-filled days. Though the temperatures rise, the weather is far from sweltering, with averages peaking at 82.8°F (28.2°C) for a high and 62.4°F (16.9°C) for a low. Weather in June »Weather in July
The peak of Herndon's summer arrives in July, bringing with it the highest temperatures of the year. July is the warmest month in Herndon, with the average high temperature reaching up to 87.8°F (31°C) and the low around 67.3°F (19.6°C). Weather in July »Weather in August
August in Herndon carries forward the balmy summer weather, with warm conditions persisting throughout the month. The month continues with a high averaging 85.6°F (29.8°C), a trend often associated with mid-late summer in Herndon. Weather in August »Weather in September
September brings about a transition from summer to fall in Herndon, with a gradual drop in temperatures. This month, the average high temperature decreases significantly to a comfortable 78.3°F (25.7°C), while the low registers at approximately 59.7°F (15.4°C). Weather in September »Weather in October
October is the month where Herndon fully embraces the autumn season. By now, the average high temperature has dwindled to a cool 66°F (18.9°C), strips of multicolored leaves coat the streets of the city, creating a vibrant and dynamic scene. Weather in October »Weather in November
November in Herndon observes a considerable drop in temperatures, heralding the arrival of winter. Monthly averages denote a high reaching 53.6°F (12°C) and a low dropping to 37.8°F (3.2°C), setting up a more wintry atmosphere. Weather in November »Weather in December
December ushers in the full charm of winter in Herndon, with temperatures steering towards the colder end of the spectrum. December sees the return of snowfall, with accumulations reaching 1.97" (50mm), welcoming in the quintessential frosty winter season. Weather in December »Updated: Jul 15, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
January stands out as Herndon's coldest month, with an average high-temperature of 39.7°F (4.3°C) and a low-temperature of 25.9°F (-3.4°C).
In Herndon, during the entire year, the rain falls for 158.1 days and collects up to 31.46" (799mm) of precipitation.
Months with snowfall are January through April, November and December.
The month with the most snowfall is January, when snow falls for 5.1 days and typically aggregates up to 3.54" (90mm) of snow.
Throughout the year, there are 16.7 snowfall days, and 12.28" (312mm) of snow is accumulated.
The months with the least sunshine in Herndon are January, February and December, with an average of 5h of sunshine.
The months with the lowest UV index in Herndon are January, February, November and December, with an average maximum UV index of 2.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts in Herndon, and the time zone changes from EST to EDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from EDT to EST.
May through October are months without snowfall.
May through August, with an average maximum UV index of 6, are months with the highest UV index.
With an average of 14h and 54min of daylight, June has the longest days of the year.
July is the warmest month, with the temperature often reaching an average high of 87.8°F (31°C) and an average low of 67.3°F (19.6°C).
With an average relative humidity of 70%, July is the least humid month.
The month with the most sunshine is July, with an average of 10.7h of sunshine.
The month with the most rainfall is August, when the rain falls for 16.7 days and typically aggregates up to 3.78" (96mm) of precipitation.
The month with the least rainfall is September, when the rain falls for 12.6 days and typically collects 1.93" (49mm) of precipitation.
The most humid month in Herndon is December, with an average relative humidity of 78%.
December has the shortest days of the year, with an average of 9h and 30min of daylight.
Average temperature
Herndon, VA
The warmest month (with the highest average high temperature) is July (87.8°F).
The month with the lowest average high temperature is January (39.7°F).
The month with the highest average low temperature is July (67.3°F).
The coldest month (with the lowest average low temperature) is January (25.9°F).
Average pressure
Herndon, VA
- Average pressure in January:
30.11"Hg - Average pressure in February:
30.07"Hg - Average pressure in March:
30.08"Hg - Average pressure in April:
29.99"Hg - Average pressure in May:
30.01"Hg - Average pressure in June:
29.95"Hg
- Average pressure in July:
29.97"Hg - Average pressure in August:
29.99"Hg - Average pressure in September:
30.05"Hg - Average pressure in October:
30.04"Hg - Average pressure in November:
30.14"Hg - Average pressure in December:
30.11"Hg
The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).
Average wind speed
Herndon, VA
- Average wind speed in January:
7.2mph - Average wind speed in February:
7.3mph - Average wind speed in March:
7.5mph - Average wind speed in April:
7.4mph - Average wind speed in May:
6mph - Average wind speed in June:
5.5mph
- Average wind speed in July:
4.8mph - Average wind speed in August:
4.7mph - Average wind speed in September:
5.3mph - Average wind speed in October:
6.2mph - Average wind speed in November:
6.5mph - Average wind speed in December:
6.6mph
The windiest month (with the highest average wind speed) is March (7.5mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).
Average humidity
Herndon, VA
The month with the highest relative humidity is December (78%).
The month with the lowest relative humidity is July (70%).
Average rainfall
Herndon, VA
- Average rainfall in January:
2.13" - Average rainfall in February:
2.2" - Average rainfall in March:
2.44" - Average rainfall in April:
2.8" - Average rainfall in May:
3.11" - Average rainfall in June:
2.48"
- Average rainfall in July:
3.03" - Average rainfall in August:
3.78" - Average rainfall in September:
1.93" - Average rainfall in October:
2.52" - Average rainfall in November:
2.36" - Average rainfall in December:
2.68"
The wettest month (with the highest rainfall) is August (3.78").
The driest month (with the least rainfall) is September (1.93").
Average rainfall days
Herndon, VA
- Average rainfall days in January:
9.3 days - Average rainfall days in February:
10.5 days - Average rainfall days in March:
13 days - Average rainfall days in April:
15.4 days - Average rainfall days in May:
17.5 days - Average rainfall days in June:
14.8 days
- Average rainfall days in July:
16.3 days - Average rainfall days in August:
16.7 days - Average rainfall days in September:
12.6 days - Average rainfall days in October:
12 days - Average rainfall days in November:
9.5 days - Average rainfall days in December:
10.5 days
The month with the highest number of rainy days is May (17.5 days).
The month with the least rainy days is January (9.3 days).
Average snowfall
Herndon, VA
The month with the highest snowfall is January (3.54").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days
Herndon, VA
- Average snowfall days in January:
5.1 days - Average snowfall days in February:
5.1 days - Average snowfall days in March:
3 days - Average snowfall days in April:
0.3 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0 days - Average snowfall days in November:
0.5 days - Average snowfall days in December:
2.7 days
The months with the highest number of snowfall days are January and February (5.1 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight / Average sunshine
Herndon, VA
- Average daylight in January:
9h and 48min - Average daylight in February:
10h and 48min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 12min - Average daylight in May:
14h and 18min - Average daylight in June:
14h and 54min
- Average daylight in July:
14h and 36min - Average daylight in August:
13h and 36min - Average daylight in September:
12h and 24min - Average daylight in October:
11h and 12min - Average daylight in November:
10h and 6min - Average daylight in December:
9h and 30min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in January:
5h and 0min - Average sunshine in February:
5h and 0min - Average sunshine in March:
6h and 36min - Average sunshine in April:
8h and 42min - Average sunshine in May:
8h and 42min - Average sunshine in June:
10h and 6min
- Average sunshine in July:
10h and 42min - Average sunshine in August:
10h and 0min - Average sunshine in September:
8h and 42min - Average sunshine in October:
5h and 30min - Average sunshine in November:
5h and 36min - Average sunshine in December:
5h and 0min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 0min).
Average sunshine days
Herndon, VA
- Average sunshine days in January:
17.2 days - Average sunshine days in February:
14.3 days - Average sunshine days in March:
15.3 days - Average sunshine days in April:
12.8 days - Average sunshine days in May:
12.1 days - Average sunshine days in June:
13.6 days
- Average sunshine days in July:
11.8 days - Average sunshine days in August:
12.1 days - Average sunshine days in September:
15.9 days - Average sunshine days in October:
17.3 days - Average sunshine days in November:
19.5 days - Average sunshine days in December:
17.5 days
The month with the most sunshine days is November (19.5 days).
The month with the least sunshine days is July (11.8 days).
Average UV index
Herndon, VA
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover
Herndon, VA
The month with the most cloud cover is March (Cloud cover 48).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility
Herndon, VA
The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).
