September weather forecastWilliston, SC
September
Weather in September
September, the first month of the autumn in Williston, is also a moderately hot month, with an average temperature varying between 84°F (28.9°C) and 67.6°F (19.8°C).Temperature
The arrival of September brings an average high-temperature of a warm 84°F (28.9°C), nearly identical to August's 88.9°F (31.6°C). In September, the average low-temperature is a comfortable 67.6°F (19.8°C).Heat index
The heat index for September is calculated to be a hot 91.4°F (33°C). Take greater precautions, heat exhaustion and heat cramps may be expected. Heatstroke could result from lengthy activity.Know that the heat index computations account for shaded terrains and slight winds. Exposure to unobstructed sunshine could lead to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'feels like', is derived by integrating air temperature with the existing relative humidity to express the perceived warmth. Elements such as metabolic variations, pregnancy, and physical exertion can shape one's weather perception. Direct sunlight can potentially raise the heat index by 15 Fahrenheit (8 Celsius) degrees, so it's crucial to consider. Heat index values are primarily vital for children. Children often overlook the necessity for resting and fluid replenishment. Thirst is a late sign of dehydration - thus, it is critical to stay hydrated, especially during extended periods of physical activities.
Humidity
In Williston, the average relative humidity in September is 74%.Rainfall
In September, the rain falls for 12.7 days. Throughout September, 1.85" (47mm) of precipitation is accumulated. Throughout the year, in Williston, there are 157.7 rainfall days, and 30.2" (767mm) of precipitation is accumulated.Snowfall
In Williston, snow does not fall in March through November.Daylight
The average length of the day in September is 12h and 22min.On the first day of September, sunrise is at 7:00 am and sunset at 7:50 pm. On the last day of the month, sunrise is at 7:19 am and sunset at 7:11 pm EDT.
Sunshine
In September, the average sunshine is 8.5h.UV index
In Williston, the average daily maximum UV index in September is 6. A UV Index value of 6 to 7 symbolizes a high health risk from unprotected exposure to Sun's UV rays for the ordinary person.Note: In September, the average maximum UV index of 6 translates into the following recommendations:
Continue precautions and advocate sun safety advice. Deterrence of sunburn is indispensable. Avoid exposure to the Sun and try to stay in the shade between 10 a.m. and 4 p.m., when UV radiation is most potent, but be aware that parasols or canopies may not offer full protection. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Williston, SC
- Average high temperature in September: 84°F
The warmest month (with the highest average high temperature) is July (90.5°F).
The month with the lowest average high temperature is January (54°F).
- Average low temperature in September: 67.6°F
The month with the highest average low temperature is July (73.4°F).
The coldest month (with the lowest average low temperature) is January (38.8°F).
Average pressure in September
Williston, SC
- Average pressure in September: 30.01"Hg
The months with the highest atmospheric pressure are January, November and December (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.97"Hg).
Average wind speed in September
Williston, SC
- Average wind speed in September: 6.4mph
The windiest months (with the highest average wind speed) are February, March and April (8.6mph).
The calmest month (with the lowest average wind speed) is August (5.8mph).
Average humidity in September
Williston, SC
- Average humidity in September: 74%
The month with the highest relative humidity is December (75%).
The months with the lowest relative humidity are January and November (70%).
Average rainfall in September
Williston, SC
- Average rainfall in September: 1.85"
The wettest month (with the highest rainfall) is December (3.35").
The driest month (with the least rainfall) is November (1.77").
Average rainfall days in September
Williston, SC
- Average rainfall days in September: 12.7 days
The month with the highest number of rainy days is July (19 days).
The month with the least rainy days is November (8.2 days).
Average snowfall in September
Williston, SC
- Average snowfall in September: 0"
The month with the highest snowfall is January (0.31").
The months with the least snowfall are March, April, May, June, July, August, September, October and November (0").
Average snowfall days in September
Williston, SC
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (0.6 days).
The months with the least snowfall days are April, May, June, July, August, September, October and November (0 days).
Average daylight in September /
Average sunshine in September
Williston, SC
- Average daylight in September: 12h and 24min
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 30min
The month with the most sunshine is July (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 24min).
Average sunshine days in September
Williston, SC
- Average sunshine days in September: 14.7 days
The month with the most sunshine days is October (20.5 days).
The month with the least sunshine days is July (9.4 days).
Average UV index in September
Williston, SC
- Average UV index in September: 6
The months with the highest UV index are June and July (UV index 7).
The months with the lowest UV index are January and December (UV index 3).
Average cloud cover in September
Williston, SC
- Average cloud cover in September: 31
The month with the most cloud cover is December (Cloud cover 42).
The month with the least cloud cover is October (Cloud cover 28).
Average visibility in September
Williston, 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).
