Expand
Contents
- Weather in January
- Weather in February
- Weather in March
- Weather in April
- Weather in May
- Weather in June
- Weather in July
- Weather in August
- Weather in September
- Weather in October
- Weather in November
- Weather in December
- Frequently asked questions
- Average temperature
- Average pressure
- Average wind speed
- Average humidity
- Average rainfall
- Average rainfall days
- Average snowfall
- Average snowfall days
- Average daylight
- Average sunshine
- Average sunshine days
- Average UV index
- Average cloud cover
- Average visibility
Weather in January
January, the same as December, is a wintry winter month in Herndon, Pennsylvania, with an average temperature fluctuating between 32.9°F (0.5°C) and 20.1°F (-6.6°C). January is the month that records the lowest temperatures, with averages ranging from a high of 32.9°F (0.5°C) to a low of 20.1°F (-6.6°C). Weather in January »
Weather in February
The last month of the winter, February, is also an icy month in Herndon, Pennsylvania, with temperature in the range of an average high of 36.7°F (2.6°C) and an average low of 22.5°F (-5.3°C). February's weather records an average high-temperature of a still wintry 36.7°F (2.6°C), showing little deviation from January. Weather in February »
Weather in March
The first month of the spring, March, is a chilly month in Herndon, Pennsylvania, with an average temperature fluctuating between 46°F (7.8°C) and 29.8°F (-1.2°C). Observing a rise in March, the average high-temperature goes from February's cold 36.7°F (2.6°C) to a frosty 46°F (7.8°C). Weather in March »
Weather in April
April in Herndon, Pennsylvania, is a mild spring month, with an average temperature fluctuating between 39.7°F (4.3°C) and 58.3°F (14.6°C). The start of April brings a rise in the average high-temperature, moving from a frosty 46°F (7.8°C) in March to a mild 58.3°F (14.6°C). Weather in April »
Weather in May
May, the last month of the spring in Herndon, is an agreeable month, with an average temperature ranging between max 69.4°F (20.8°C) and min 49.3°F (9.6°C). The shift from April to May sees an increase in the average high-temperature, transitioning from a refreshing 58.3°F (14.6°C) to a pleasant 69.4°F (20.8°C). Weather in May »
Weather in June
The first month of the summer, June, is a warm month in Herndon, Pennsylvania, with an average temperature varying between 56.5°F (13.6°C) and 77°F (25°C). The shift from May to June is marked by a slight increase in the average high-temperature, moving from a pleasant 69.4°F (20.8°C) to a warm 77°F (25°C). Weather in June »
Weather in July
July, like June, in Herndon, Pennsylvania, is another warm summer month, with an average temperature varying between 61.2°F (16.2°C) and 82.4°F (28°C). With average temperatures fluctuating between a high of 82.4°F (28°C) and a low of 61.2°F (16.2°C), July stands out as the warmest month. July's mean heat index is calculated to be a hot 89.6°F (32°C). Weather in July »
Weather in August
The last month of the summer, August, is another warm month in Herndon, Pennsylvania, with temperature in the range of an average low of 59.2°F (15.1°C) and an average high of 80.2°F (26.8°C). Herndon measures an average high-temperature of a still warm 80.2°F (26.8°C) in August, nearly consistent with the preceding month. Weather in August »
Weather in September
September, the first month of the autumn in Herndon, is also a moderately hot month, with an average temperature varying between 53.6°F (12°C) and 73.8°F (23.2°C). September's onset brings a negligible change in high-temperatures, falling from a warm 80.2°F (26.8°C) in August to a still moderately hot 73.8°F (23.2°C). Weather in September »
Weather in October
October, like September, in Herndon, Pennsylvania, is another comfortable autumn month, with an average temperature varying between 44.2°F (6.8°C) and 61.3°F (16.3°C). With October's arrival, Herndon sees a decrease in average high-temperatures, moving from a warm 73.8°F (23.2°C) in September to an enjoyable 61.3°F (16.3°C). Weather in October »
Weather in November
November, the last month of the autumn in Herndon, is another chilly month, with an average temperature ranging between max 48.4°F (9.1°C) and min 34°F (1.1°C). The onset of November entails a temperature shift, as the average high-temperature decreases from an enjoyable 61.3°F (16.3°C) in October to a frosty 48.4°F (9.1°C). Weather in November »
Weather in December
The first month of the winter, December, is still a cold month in Herndon, Pennsylvania, with an average temperature fluctuating between 28°F (-2.2°C) and 39°F (3.9°C). The arrival of December corresponds with a reduction in the average high-temperature, down from November's chilly 48.4°F (9.1°C) to a cold 39°F (3.9°C). Weather in December »
Frequently asked questions
What are the coldest months?
January tends to be the coldest month, with temperatures averaging a daily high of 32.9°F (0.5°C) and a low of 20.1°F (-6.6°C).
How much does it rain?
Throughout the year, there are 165.3 rainfall days, and 30.55" (776mm) of precipitation is accumulated.
When does it snow?
January through May, October through December are months with snowfall.
How much does it snow?
Throughout the year, there are 38.1 snowfall days, and 17.68" (449mm) of snow is accumulated.
What are the months with the lowest UV index?
The months with the lowest UV index are January through March, November and December, with an average maximum UV index of 2.
What is the most humid month?
With an average relative humidity of 82%, February is the most humid month.
What is the driest month?
The months with the least rainfall are February and November Rain falls for 9 days and accumulates 2.09" (53mm) of rain.
What is the snowiest month?
February is the month with the most snowfall. Snow falls for 10.2 days and accumulates 5.67" (144mm) of snow.
What is the month with the least sunshine?
The month with the least sunshine is February, with an average of 4.2h of sunshine.
When is Daylight Saving Time (DST)?
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, 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.
What is the least humid month?
April is the least humid month, with an average relative humidity of 76%.
What is the wettest month?
The month with the most rainfall is May, when the rain falls for 18.4 days and typically aggregates up to 3.35" (85mm) of precipitation.
When it does not snow?
In Herndon, snow does not fall in June through September.
When are the longest days?
The month with the longest days is June, with an average of 15h and 0min of daylight.
What are the months with the highest UV index?
June and July, with an average maximum UV index of 6, are months with the highest UV index.
What are the warmest months?
Herndon's temperature records reveal July as the warmest month, marked by average highs of 82.4°F (28°C) and lows of 61.2°F (16.2°C).
What month has the most sunshine?
July has the most sunshine of the year, with an average of 10.4h of sunshine.
What is the month with the shortest days?
December has the shortest days of the year, with an average of 9h and 18min of daylight.
Average temperature
Herndon, PA
The warmest month (with the highest average high temperature) is July (82.4°F).
The month with the lowest average high temperature is January (32.9°F).
The month with the highest average low temperature is July (61.2°F).
The coldest month (with the lowest average low temperature) is January (20.1°F).
Average pressure
Herndon, PA
- Average pressure in January:
30.09"Hg - Average pressure in February:
30.06"Hg - Average pressure in March:
30.08"Hg - Average pressure in April:
29.98"Hg - Average pressure in May:
30.01"Hg - Average pressure in June:
29.94"Hg
- Average pressure in July:
29.98"Hg - Average pressure in August:
30"Hg - Average pressure in September:
30.07"Hg - Average pressure in October:
30.04"Hg - Average pressure in November:
30.13"Hg - Average pressure in December:
30.1"Hg
The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).
Average wind speed
Herndon, PA
- Average wind speed in January:
7.5mph - Average wind speed in February:
7.4mph - Average wind speed in March:
7.8mph - Average wind speed in April:
7.8mph - Average wind speed in May:
6.1mph - Average wind speed in June:
5.7mph
- Average wind speed in July:
4.7mph - Average wind speed in August:
4.5mph - Average wind speed in September:
5.2mph - Average wind speed in October:
6.3mph - Average wind speed in November:
6.6mph - Average wind speed in December:
7mph
The windiest months (with the highest average wind speed) are March and April (7.8mph).
The calmest month (with the lowest average wind speed) is August (4.5mph).
Average humidity
Herndon, PA
The month with the highest relative humidity is February (82%).
The month with the lowest relative humidity is April (76%).
Average rainfall
Herndon, PA
- Average rainfall in January:
2.2" - Average rainfall in February:
2.09" - Average rainfall in March:
2.36" - Average rainfall in April:
3.19" - Average rainfall in May:
3.35" - Average rainfall in June:
2.64"
The wettest month (with the highest rainfall) is May (3.35").
The driest months (with the least rainfall) are February and November (2.09").
Average rainfall days
Herndon, PA
- Average rainfall days in January:
9.3 days - Average rainfall days in February:
9 days - Average rainfall days in March:
13 days - Average rainfall days in April:
17.8 days - Average rainfall days in May:
18.4 days - Average rainfall days in June:
15.7 days
- Average rainfall days in July:
16.5 days - Average rainfall days in August:
15.6 days - Average rainfall days in September:
12.6 days - Average rainfall days in October:
14.3 days - Average rainfall days in November:
11.3 days - Average rainfall days in December:
11.8 days
The month with the highest number of rainy days is May (18.4 days).
The month with the least rainy days is February (9 days).
Average snowfall
Herndon, PA
- Average snowfall in January:
4.41" - Average snowfall in February:
5.67" - Average snowfall in March:
3.78" - Average snowfall in April:
0.35" - Average snowfall in May:
0.16" - Average snowfall in June:
0"
The month with the highest snowfall is February (5.67").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days
Herndon, PA
- Average snowfall days in January:
11.3 days - Average snowfall days in February:
10.2 days - Average snowfall days in March:
6.3 days - Average snowfall days in April:
1 days - Average snowfall days in May:
0.3 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:
0.1 days - Average snowfall days in November:
1.9 days - Average snowfall days in December:
7 days
The month with the highest number of snowfall days is January (11.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight / Average sunshine
Herndon, PA
- Average daylight in January:
9h and 4min - Average daylight in February:
10h and 4min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 2min - Average daylight in May:
14h and 3min - Average daylight in June:
15h and 0min
- Average daylight in July:
14h and 4min - Average daylight in August:
13h and 4min - Average daylight in September:
12h and 3min - Average daylight in October:
11h and 1min - Average daylight in November:
9h and 5min - Average daylight in December:
9h and 2min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in January:
4h and 2min - Average sunshine in February:
4h and 1min - Average sunshine in March:
6h and 2min - Average sunshine in April:
8h and 0min - Average sunshine in May:
8h and 2min - Average sunshine in June:
10h and 0min
- Average sunshine in July:
10h and 2min - Average sunshine in August:
10h and 1min - Average sunshine in September:
8h and 5min - Average sunshine in October:
5h and 2min - Average sunshine in November:
5h and 2min - Average sunshine in December:
4h and 2min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is February (Average sunshine: 4h and 12min).
Average sunshine days
Herndon, PA
- Average sunshine days in January:
13.9 days - Average sunshine days in February:
10.8 days - Average sunshine days in March:
13 days - Average sunshine days in April:
10.9 days - Average sunshine days in May:
9.9 days - Average sunshine days in June:
12.5 days
- Average sunshine days in July:
12.5 days - Average sunshine days in August:
13.5 days - Average sunshine days in September:
15.4 days - Average sunshine days in October:
14.3 days - Average sunshine days in November:
16.4 days - Average sunshine days in December:
14.6 days
The month with the most sunshine days is November (16.4 days).
The month with the least sunshine days is May (9.9 days).
Average UV index
Herndon, PA
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover
Herndon, PA
The month with the most cloud cover is February (Cloud cover 54).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility
Herndon, PA
The months with the highest visibility are March, April, June, July and November (6mi).
The months with the lowest visibility are January, February, May, August, September, October and December (5mi).
Herndon, Pennsylvania, USA
Weather forecast for your location
1. Click Locate me button
2. Allow the app to use your location
2. Allow the app to use your location
