Climate and monthly weather forecast
Herndon, PA

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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 »

Frequently asked questions

What month is the coldest?

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.

How many days 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.

When is 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?

The most humid month is February, with an average relative humidity of 82%.

What is the driest month?

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.

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?

With an average of 4.2h of sunshine, February has the least sunshine of the year.

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?

June through September are months without snowfall.

When are the longest days?

The month with the longest days is June, with an average of 15h and 0min of daylight.

What is the month 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?

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.

What month has the most sunshine?

The month with the most sunshine is July, 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

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 - Herndon, PA

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 - Herndon, PA

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

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 - Herndon, PA

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 - Herndon, PA

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 - Herndon, PA

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 - Herndon, PA

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 / Average sunshine - Herndon, PA

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).

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 - Herndon, PA

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

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 visibility
Herndon, PA

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

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