Climate and monthly weather forecastHerndon, PA
Climate and monthly weather forecast
Weather in January
January, like December, in Herndon, Pennsylvania, is a wintry winter month, with an average temperature ranging between min 20.1°F (-6.6°C) and max 32.9°F (0.5°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 another cold month in Herndon, Pennsylvania, with an average temperature fluctuating between 22.5°F (-5.3°C) and 36.7°F (2.6°C). A minor adjustment in Herndon's average high-temperature is noted with the start of February, touching a still wintry 36.7°F (2.6°C) from January's 32.9°F (0.5°C). Weather in February »Weather in March
March, the first month of the spring in Herndon, is a chilly month, with an average temperature varying between 29.8°F (-1.2°C) and 46°F (7.8°C). With the arrival of March, the average high-temperature transitions from an icy 36.7°F (2.6°C) in February to a frosty 46°F (7.8°C). Weather in March »Weather in April
April is a moderate spring month in Herndon, Pennsylvania, with an average temperature varying between 58.3°F (14.6°C) and 39.7°F (4.3°C). With the onset of April, the average high-temperature slightly shifts from March's chilly 46°F (7.8°C) to a moderate 58.3°F (14.6°C). Weather in April »Weather in May
May, the last month of the spring in Herndon, is a pleasant month, with an average temperature fluctuating between 69.4°F (20.8°C) and 49.3°F (9.6°C). A rise in the average high-temperature is observed during May, moving from a mild 58.3°F (14.6°C) in April to an agreeable 69.4°F (20.8°C). Weather in May »Weather in June
The first month of the summer, June, is a moderately hot month in Herndon, Pennsylvania, with an average temperature fluctuating between 56.5°F (13.6°C) and 77°F (25°C). Herndon's transition into June is marked by a minor temperature shift, moving from an agreeable 69.4°F (20.8°C) in May 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 ranging between min 61.2°F (16.2°C) and max 82.4°F (28°C). July, known for its average high temperature of 82.4°F (28°C) and an average low temperature of 61.2°F (16.2°C), is the warmest month. For July, the heat index is appraised at a tropical 89.6°F (32°C). Weather in July »Weather in August
August, the last month of the summer in Herndon, is also a moderately hot month, with an average temperature ranging between max 80.2°F (26.8°C) and min 59.2°F (15.1°C). The arrival of August coincides with an average high-temperature of a still warm 80.2°F (26.8°C), indicating a minimal shift from July's 82.4°F (28°C). Weather in August »Weather in September
September, the first month of the autumn in Herndon, is still a warm month, with an average temperature ranging between min 53.6°F (12°C) and max 73.8°F (23.2°C). Herndon, Pennsylvania, in September undergoes a slight reduction in the average high-temperature, shifting from August's 80.2°F (26.8°C) to a still warm 73.8°F (23.2°C). Weather in September »Weather in October
October, the same as September, is another comfortable autumn month in Herndon, Pennsylvania, with temperature in the range of an average low of 44.2°F (6.8°C) and an average high of 61.3°F (16.3°C). October ushers in a slight temperature change, with average high-temperatures reducing from September's warm 73.8°F (23.2°C) to a comfortable 61.3°F (16.3°C). Weather in October »Weather in November
The last month of the autumn, November, is another chilly month in Herndon, Pennsylvania, with an average temperature fluctuating between 34°F (1.1°C) and 48.4°F (9.1°C). The move into November indicates a reduction in the average high-temperature, down from October's refreshing 61.3°F (16.3°C) to a chilly 48.4°F (9.1°C). Weather in November »Weather in December
December, the first month of the winter in Herndon, is also a wintry month, with an average temperature fluctuating between 28°F (-2.2°C) and 39°F (3.9°C). December comes with a decrease in the average high-temperature, falling from a chilly 48.4°F (9.1°C) in November to a wintry 39°F (3.9°C). Weather in December »Updated: Jun 6, 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, with an average high of 32.9°F (0.5°C) and a low of 20.1°F (-6.6°C), signifies the coldest month of the year.
Throughout the year, there are 165.3 rainfall days, and 30.55" (776mm) of precipitation is accumulated.
January through May, October through December are months with snowfall.
Throughout the year, there are 38.1 snowfall days, and 17.68" (449mm) of snow is accumulated.
The months with the lowest UV index are January through March, November and December, with an average maximum UV index of 2.
The most humid month is February, with an average relative humidity of 82%.
February and November are months with the least rain in Herndon when the rain falls for 9 days and typically aggregates up to 2.09" (53mm) of rain.
February is the month with the most snowfall. Snow falls for 10.2 days and accumulates 5.67" (144mm) of snow.
With an average of 4.2h of sunshine, February has the least sunshine of the year.
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.
April is the least humid month, with an average relative humidity of 76%.
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.
June through September are months without snowfall.
The month with the longest days is June, with an average of 15h and 0min of daylight.
June and July, with an average maximum UV index of 6, are months with the highest UV index.
July, characterized by an average high temperature of 82.4°F (28°C) and a low temperature of 61.2°F (16.2°C), is generally the warmest month.
The month with the most sunshine is July, with an average of 10.4h of sunshine.
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 42min - Average daylight in February:
10h and 42min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 18min - Average daylight in May:
14h and 30min - Average daylight in June:
15h and 0min
- Average daylight in July:
14h and 42min - Average daylight in August:
13h and 42min - Average daylight in September:
12h and 30min - Average daylight in October:
11h and 6min - Average daylight in November:
9h and 54min - Average daylight in December:
9h and 18min
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 18min - Average sunshine in February:
4h and 12min - Average sunshine in March:
6h and 18min - Average sunshine in April:
8h and 0min - Average sunshine in May:
8h and 24min - Average sunshine in June:
10h and 0min
- Average sunshine in July:
10h and 24min - Average sunshine in August:
10h and 6min - Average sunshine in September:
8h and 48min - Average sunshine in October:
5h and 18min - Average sunshine in November:
5h and 24min - Average sunshine in December:
4h and 24min
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).
