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
With the arrival of September, Great Falls notices a mild change in the average high-temperature, sliding from August's 85.6°F (29.8°C) to a still warm 78.4°F (25.8°C). An average temperature of 60.8°F (16°C) is recorded in Great Falls during the nights in September.Humidity
In September, the average relative humidity in Great Falls is 74%.Rainfall
In Great Falls, during September, the rain falls for 12.5 days and regularly aggregates up to 1.93" (49mm) of precipitation. In Great Falls, Virginia, during the entire year, the rain falls for 152.8 days and collects up to 27.64" (702mm) of precipitation.Snowfall
In Great Falls, snow does not fall in May through October.Daylight
In September, the average length of the day is 12h and 26min.On the first day of the month, sunrise is at 6:38 am and sunset at 7:39 pm. On the last day of September, sunrise is at 7:04 am and sunset at 6:52 pm EDT.
Sunshine
The average sunshine in September in Great Falls is 8.7h.UV index
The average daily maximum UV index in September in Great Falls, Virginia, is 5. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for ordinary individuals.Note: The UV index of 5 during September translates into the following guidance:
Take precautions - Protection against sunburn is recommended. When the Sun is at its strongest around midday, find shade and limit exposure. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.
Frequently asked questions
What are the temperatures in Great Falls in September?
What is the average humidity in September in Great Falls?
How much does it rain in Great Falls in September?
When it does not snow in Great Falls?
How many hours of daylight does Great Falls have in September?
When are sunrise and sunset in September in Great Falls?
How many hours of sunshine does Great Falls have in September?
How high is the UV index in September in Great Falls?
Average temperature in September
Great Falls, VA
- Average high temperature in September: 78.4°F
The warmest month (with the highest average high temperature) is July (87.6°F).
The month with the lowest average high temperature is January (39.7°F).
- Average low temperature in September: 60.8°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (26.4°F).
Average pressure in September
Great Falls, VA
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).
Average wind speed in September
Great Falls, VA
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is March (7.7mph).
The calmest month (with the lowest average wind speed) is August (4.9mph).
Average humidity in September
Great Falls, VA
- Average humidity in September: 74%
The months with the highest relative humidity are October and December (76%).
The month with the lowest relative humidity is July (69%).
Average rainfall in September
Great Falls, VA
- Average rainfall in September: 1.93"
The wettest month (with the highest rainfall) is August (3.39").
The driest month (with the least rainfall) is January (1.77").
Average rainfall days in September
Great Falls, VA
- Average rainfall days in September: 12.5 days
The month with the highest number of rainy days is May (16.3 days).
The month with the least rainy days is November (9.3 days).
Average snowfall in September
Great Falls, VA
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.28").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Great Falls, VA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (4.6 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Great Falls, VA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 8h and 4min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 0min).
Average sunshine days in September
Great Falls, VA
- Average sunshine days in September: 16.3 days
The month with the most sunshine days is November (19.3 days).
The month with the least sunshine days is May (12.8 days).
Average UV index in September
Great Falls, VA
- Average UV index in September: 5
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Great Falls, VA
- Average cloud cover in September: 38
The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility in September
Great Falls, VA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).
Great Falls, Virginia, USA
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