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
The transition to May introduces an increase in the average high-temperature, shifting from a refreshing 58.3°F (14.6°C) in April to an agreeable 69.4°F (20.8°C). During May, Herndon records a consistent average nighttime temperature of 49.3°F (9.6°C).Humidity
In May, the average relative humidity in Herndon is 80%.Rainfall
May is the month with the most rainfall in Herndon. Rain falls for 18.4 days and accumulates 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. In Herndon, Pennsylvania, during the entire year, snow falls for 38.1 days and aggregates up to 17.68" (449mm) of snow.Daylight
The average length of the day in May in Herndon 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
In May, the average sunshine is 8.4h.UV index
In Herndon, the average daily maximum UV index in May is 5. A UV Index reading of 3 to 5 represents a moderate threat to health from unsafe exposure to UV radiation for the average person.Note: A daily maximum UV index of 5 in May translates into the following instructions:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The midday Sun can be harmful due to its potent UV radiation; seek shade and reduce exposure. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays. Keep in mind! Snow's reflective quality can nearly double the intensity of the Sun's UV radiation.
Frequently asked questions
What are May temperatures in Herndon?
What is the average humidity in May in Herndon?
What is the rainiest month in Herndon?
How much does it rain in Herndon in May?
What is the last month it snows in Herndon?
How many hours of daylight does Herndon have in May?
When are sunrise and sunset in May in Herndon?
How many hours of sunshine does Herndon have in May?
What is the UV index reading in May in Herndon?
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
Weather forecast for your location
2. Allow the app to use your location
