Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The arrival of September suggests a slight decrease in the average high-temperature, moving from 82°F (27.8°C) in August to a still warm 76.3°F (24.6°C). Keystone's nighttime temperatures in September reflect a stark contrast to the day's highs, falling to an average low of 54.1°F (12.3°C).Humidity
The average relative humidity in September in Keystone is 78%.Rainfall
September is the month with the least rainfall. Rain falls for 15.2 days and accumulates 1.54" (39mm) of precipitation.Snowfall
In Keystone, West Virginia, snow does not fall in June through September.Daylight
The average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:56 am and sunset at 7:54 pm. On the last day of September, sunrise is at 7:21 am and sunset at 7:10 pm EDT.
Sunshine
The average sunshine in September is 8.4h.UV index
In Keystone, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for ordinary individuals.Note: In September, a daily maximum UV index of 4 leads to the following instructions:
Exercise prevention - Warding off sunburn is urged. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
Frequently asked questions
What is the average September temperature in Keystone?
What is the average humidity in September in Keystone?
What is the driest month in Keystone?
How much does it rain in Keystone in September?
When it does not snow in Keystone?
Does it snow in Keystone in September?
What is the average length of the day in September in Keystone?
When is the sunrise / sunset in September in Keystone?
How many hours of sunshine does Keystone have in September?
How high is the UV index in September in Keystone?
Average temperature in September
Keystone, WV
- Average high temperature in September: 76.3°F
The warmest month (with the highest average high temperature) is July (83.5°F).
The month with the lowest average high temperature is January (39.2°F).
- Average low temperature in September: 54.1°F
The month with the highest average low temperature is July (60.3°F).
The coldest month (with the lowest average low temperature) is January (25°F).
Average pressure in September
Keystone, WV
- Average pressure in September: 30.06"Hg
The month with the highest atmospheric pressure is November (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.99"Hg).
Average wind speed in September
Keystone, WV
- Average wind speed in September: 4.5mph
The windiest month (with the highest average wind speed) is January (7.3mph).
The calmest month (with the lowest average wind speed) is August (4.2mph).
Average humidity in September
Keystone, WV
- Average humidity in September: 78%
The month with the highest relative humidity is February (82%).
The months with the lowest relative humidity are July, August and November (76%).
Average rainfall in September
Keystone, WV
- Average rainfall in September: 1.54"
The wettest month (with the highest rainfall) is May (3.19").
The driest month (with the least rainfall) is September (1.54").
Average rainfall days in September
Keystone, WV
- Average rainfall days in September: 15.2 days
The month with the highest number of rainy days is May (19.7 days).
The months with the least rainy days are January and November (10.1 days).
Average snowfall in September
Keystone, WV
- Average snowfall in September: 0"
The month with the highest snowfall is December (4.41").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Keystone, WV
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (10.5 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Keystone, WV
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 8h and 2min
The month with the most sunshine is August (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in September
Keystone, WV
- Average sunshine days in September: 11.8 days
The month with the most sunshine days is November (17.9 days).
The month with the least sunshine days is May (9.2 days).
Average UV index in September
Keystone, WV
- Average UV index in September: 4
The months with the highest UV index are June and August (UV index 6).
The months with the lowest UV index are January, February and December (UV index 2).
Average cloud cover in September
Keystone, WV
- Average cloud cover in September: 39
The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are June and August (Cloud cover 36).
Average visibility in September
Keystone, WV
- Average visibility in September: 5mi
The months with the highest visibility are April and November (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October and December (5mi).
Keystone, West Virginia, USA
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