Contents
- Weather in May
- Frequently asked questions
- Average temperature in May
- Average pressure in May
- Average wind speed in May
- Average humidity in May
- Average rainfall in May
- Average rainfall days in May
- Average snowfall in May
- Average snowfall days in May
- Average daylight in May
- Average sunshine in May
- Average sunshine days in May
- Average UV index in May
- Average cloud cover in May
- Average visibility in May
Weather in May
Temperature
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). Throughout May, Herndon anticipates an average low-temperature of 49.3°F (9.6°C).Humidity
In Herndon, the average relative humidity in May is 80%.Rainfall
The month with the most rainfall in Herndon is May, when the rain falls for 18.4 days and typically aggregates up to 3.35" (85mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. May is the last month it regularly snows. During 0.3 snowfall days, in May, Herndon aggregates 0.16" (4mm) of snow. Throughout the year, there are 38.1 snowfall days, and 17.68" (449mm) of snow is accumulated.Daylight
The average length of the day in May is 14h and 28min.On the first day of the month, sunrise is at 6:04 am and sunset at 8:03 pm. On the last day of May, sunrise is at 5:38 am and sunset at 8:31 pm EDT.
Sunshine
The average sunshine in May is 8.4h.UV index
The average daily maximum UV index in May in Herndon is 5. A UV Index reading of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for the average person.Note: An average UV index of 5 in May transforms into this advice:
Undertake protective steps - Preventing sun damage is advised. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears. Keep in mind! Snow's reflective quality can nearly double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average May temperature in Herndon?
What is the average humidity in May?
What is the wettest month?
How many days does it rain in May in Herndon?
What is the last month it snows?
What is the average length of the day in May?
When is the sunrise / sunset in May?
How long on average sun shines in May?
What is the UV index reading in May?
Average temperature in May
Herndon, PA
- Average high temperature in May: 69.4°F
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).
- Average low temperature in May: 49.3°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 in May
Herndon, PA
- Average pressure in May: 30.01"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 in May
Herndon, PA
- Average wind speed in May: 6.1mph
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 in May
Herndon, PA
- Average humidity in May: 80%
The month with the highest relative humidity is February (82%).
The month with the lowest relative humidity is April (76%).
Average rainfall in May
Herndon, PA
- Average rainfall in May: 3.35"
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 in May
Herndon, PA
- Average rainfall days in May: 18.4 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 in May
Herndon, PA
- Average snowfall in May: 0.16"
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 in May
Herndon, PA
- Average snowfall days in May: 0.3 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 in May /
Average sunshine in May
Herndon, PA
- Average daylight in May: 14h and 3min
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 May: 8h 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 in May
Herndon, PA
- Average sunshine days in May: 9.9 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 in May
Herndon, PA
- Average UV index in May: 5
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 in May
Herndon, PA
- Average cloud cover in May: 47
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 in May
Herndon, PA
- Average visibility in May: 5mi
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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