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
September's onset sees an average high-temperature of a warm 84.9°F (29.4°C), exhibiting a slight fluctuation from the previous month. In September, Fairfax's temperature tends to fall to an average low of 68.2°F (20.1°C) during the night.Heat index
September's mean heat index is evaluated at a very hot 95°F (35°C). Apply extra caution, heat cramps and heat exhaustion could happen. Heatstroke might occur with long-duration activity.Take into consideration that the heat index values are calculated for shade and light wind conditions. When exposed to the direct sun, the heat index may augment by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'feels like', embodies the combination of air temperature and moisture content to illustrate perceived heat. The influence of weather is personal, differing among individuals based on variations in body mass, stature, and the degree of physical exertion. One should be aware that direct sunshine can amplify the perceived temperature, raising the heat index by as much as 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
The body's natural response to excessive warmth is perspiration, as it allows for cooling through sweat evaporation. In conditions of both high temperature and humidity (a high heat index), sweating is limited and the perception of heat is enhanced. Accumulating heat beyond the body's cooling measures leads to rising temperatures and potential ailments.
Humidity
The average relative humidity in September is 75%.Rainfall
In September, the rain falls for 13.9 days. Throughout September, 1.97" (50mm) of precipitation is accumulated. Throughout the year, there are 152.9 rainfall days, and 31.18" (792mm) of precipitation is accumulated.Snowfall
In Fairfax, snow does not fall in March through December.Daylight
In September, the average length of the day is 12h and 22min.On the first day of the month, sunrise is at 6:59 am and sunset at 7:49 pm. On the last day of September, sunrise is at 7:18 am and sunset at 7:10 pm EDT.
Sunshine
In Fairfax, the average sunshine in September is 8.4h.UV index
In Fairfax, the average daily maximum UV index in September is 6. A UV Index estimate of 6 to 7 represents a high health risk from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In September, a regular UV index of 6 translates into these guidelines:
Take precautions against overexposure. Protection against sun damage is needed. The hours from 10 a.m. to 4 p.m. have the most intense UV radiation. As much as possible, limit direct sun exposure during this period. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Is it hot during September?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
What is the average length of the day in September?
When are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
Fairfax, SC
- Average high temperature in September: 84.9°F
The warmest month (with the highest average high temperature) is July (91°F).
The month with the lowest average high temperature is January (55.4°F).
- Average low temperature in September: 68.2°F
The month with the highest average low temperature is July (73.2°F).
The coldest month (with the lowest average low temperature) is January (39.9°F).
Average pressure in September
Fairfax, SC
- Average pressure in September: 30"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.97"Hg).
Average wind speed in September
Fairfax, SC
- Average wind speed in September: 5.9mph
The windiest month (with the highest average wind speed) is April (7.6mph).
The calmest month (with the lowest average wind speed) is August (5.4mph).
Average humidity in September
Fairfax, SC
- Average humidity in September: 75%
The months with the highest relative humidity are August and December (76%).
The month with the lowest relative humidity is January (70%).
Average rainfall in September
Fairfax, SC
- Average rainfall in September: 1.97"
The wettest month (with the highest rainfall) is August (3.7").
The driest month (with the least rainfall) is November (1.38").
Average rainfall days in September
Fairfax, SC
- Average rainfall days in September: 13.9 days
The month with the highest number of rainy days is August (20.8 days).
The month with the least rainy days is November (6.6 days).
Average snowfall in September
Fairfax, SC
- Average snowfall in September: 0"
The month with the highest snowfall is February (0.12").
The months with the least snowfall are March, April, May, June, July, August, September, October, November and December (0").
Average snowfall days in September
Fairfax, SC
- Average snowfall days in September: 0 days
The months with the highest number of snowfall days are January and February (0.3 days).
The months with the least snowfall days are March, April, May, June, July, August, September, October, November and December (0 days).
Average daylight in September /
Average sunshine in September
Fairfax, SC
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).
- Average sunshine in September: 8h and 2min
The month with the most sunshine is July (Average sunshine: 10h and 48min).
The month with the least sunshine is December (Average sunshine: 5h and 18min).
Average sunshine days in September
Fairfax, SC
- Average sunshine days in September: 14.3 days
The month with the most sunshine days is November (22.3 days).
The month with the least sunshine days is August (7.3 days).
Average UV index in September
Fairfax, SC
- Average UV index in September: 6
The months with the highest UV index are June, July and August (UV index 7).
The months with the lowest UV index are January and December (UV index 3).
Average cloud cover in September
Fairfax, SC
- Average cloud cover in September: 33
The months with the most cloud cover are February and December (Cloud cover 43).
The month with the least cloud cover is October (Cloud cover 29).
Average visibility in September
Fairfax, SC
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Fairfax, South Carolina, USA
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