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 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
As August turns into September, the average high-temperatures rest at a still warm 82.9°F (28.3°C), showing a minor variation from the prior month. Nighttime temperatures during September report a consistent average of 74.3°F (23.5°C).Heat index
The heat index value during September is appraised at a hot 89.6°F (32°C). If one continues to be active during enduring exposure, it could result in fatigue and heat cramps.For clarity, heat index numbers account for light winds and areas under shade. The direct sun can potentially cause the heat index to increase by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'feels like', is a single figure representing how weather conditions feel when combining temperature and humidity. The influence of weather is personal, differing among individuals based on variations in body mass, stature, and the degree of physical exertion. Being aware that direct sunlight can impact the felt heat might mean an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are of high significance for children. Younglings are generally more in peril than adults due to their reduced perspiration. Coupled with a larger skin surface relative to their tiny bodies and greater heat production because of their activity, they become more at risk.
Humidity
In Sullivan's Island, the average relative humidity in September is 76%.Rainfall
In Sullivan's Island, in September, it is raining for 19.2 days, with typically 5.71" (145mm) of accumulated precipitation. In Sullivan's Island, during the entire year, the rain falls for 182 days and collects up to 45.55" (1157mm) of precipitation.Snowfall
In Sullivan's Island, 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 September, sunrise is at 6:54 am and sunset at 7:43 pm. On the last day of the month, sunrise is at 7:13 am and sunset at 7:04 pm EDT.
Sunshine
In September, the average sunshine is 9.2h.UV index
In Sullivan's Island, the average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health risk from unprotected exposure to Sun's UV rays for the ordinary person.Note: The UV index of 6 in September translates into these instructions:
Follow precautions and abide by sun safety rules. Deterrence of sunburn is imperative. Remember that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. Make an effort to avoid direct sun exposure during these hours. Boost your sun resistance with garments that are densely woven yet spacious.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot does it get in September?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
How many hours of daylight does Sullivan's Island have in September?
When are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index reading in September?
Average temperature in September
Sullivan's Island, SC
- Average high temperature in September: 82.9°F
The warmest month (with the highest average high temperature) is July (86.5°F).
The month with the lowest average high temperature is January (57°F).
- Average low temperature in September: 74.3°F
The month with the highest average low temperature is July (78.3°F).
The coldest month (with the lowest average low temperature) is January (45.5°F).
Average pressure in September
Sullivan's Island, 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 (29.98"Hg).
Average wind speed in September
Sullivan's Island, SC
- Average wind speed in September: 9.2mph
The windiest months (with the highest average wind speed) are March and April (10.3mph).
The calmest month (with the lowest average wind speed) is August (8.4mph).
Average humidity in September
Sullivan's Island, SC
- Average humidity in September: 76%
The month with the highest relative humidity is December (78%).
The months with the lowest relative humidity are January and March (73%).
Average rainfall in September
Sullivan's Island, SC
- Average rainfall in September: 5.71"
The wettest month (with the highest rainfall) is August (8.23").
The driest month (with the least rainfall) is January (1.42").
Average rainfall days in September
Sullivan's Island, SC
- Average rainfall days in September: 19.2 days
The month with the highest number of rainy days is August (25.9 days).
The month with the least rainy days is November (8.5 days).
Average snowfall days in September
Sullivan's Island, SC
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (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
Sullivan's Island, 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: 9h and 1min
The month with the most sunshine is July (Average sunshine: 11h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).
Average sunshine days in September
Sullivan's Island, SC
- Average sunshine days in September: 7.9 days
The month with the most sunshine days is January (19.3 days).
The month with the least sunshine days is August (2.8 days).
Average UV index in September
Sullivan's Island, SC
- Average UV index in September: 6
The months with the highest UV index are May, June, July and August (UV index 7).
The month with the lowest UV index is January (UV index 3).
Average cloud cover in September
Sullivan's Island, SC
- Average cloud cover in September: 28
The month with the most cloud cover is December (Cloud cover 39).
The month with the least cloud cover is June (Cloud cover 25).
Average visibility in September
Sullivan's Island, 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).
Sullivan's Island, South Carolina, USA
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