September weather forecastCharleston, SC
September
Weather in September
September is a month of transition for Charleston. The weather takes on a more temperate feel as autumn sets in. Decreasing daily sunshine hours and a subtle dip in temperatures mark the shift from summer to autumn. Despite this, rainfall volume born out at 5" (127mm), indicates that wet weather is still expected.Temperature
The onset of September brings with it an average high-temperature of a moderately hot 83.5°F (28.6°C), showing a negligible variation from the month before. September in Charleston witnesses an average low-temperature hovering around an agreeable 73°F (22.8°C).Heat index
The heat index for September is calculated to be a hot 91.4°F (33°C). Implement additional cautionary measures, heat cramps and heat exhaustion could occur. Prolonged activity might induce heatstroke.Note that heat index values are valued for light wind and location in the shade. Uninterrupted exposure to the sun may boost the heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', is an aggregate value of air's warmth and moisture to show the human-felt temperature. This effect is personal, shaped by the individual's physical activity and heat sensitivity, influenced by factors including wind, clothing, and metabolic variances. Direct exposure to the sun's rays can enhance the felt temperature, increasing the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Young ones are generally more prone to risk than adults due to their reduced ability to sweat. Their large skin surface area relative to their diminutive bodies and elevated heat production from their activities further enhance this risk.
Humidity
In Charleston, South Carolina, the average relative humidity in September is 75%.Rainfall
In Charleston, in September, it is raining for 18.4 days, with typically 5" (127mm) of accumulated precipitation. Throughout the year, in Charleston, South Carolina, there are 178.9 rainfall days, and 41.93" (1065mm) of precipitation is accumulated.Snowfall
In Charleston, snow does not fall in February through November.Ocean temperature
In September, the average ocean temperature is 81.7°F (27.6°C).Note: Water temperature from 77°F (25°C) to 84.2°F (29°C) is considered very warm, making water activities enjoyable for prolonged periods without any uncomfortable sensations.
Daylight
The average length of the day in September in Charleston is 12h and 22min.On the first day of the month, sunrise is at 6:54 am and sunset at 7:44 pm. On the last day of September, sunrise is at 7:13 am and sunset at 7:05 pm EDT.
Sunshine
In Charleston, the average sunshine in September is 9.1h.UV index
The average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health hazard from exposure to the Sun's UV radiation for the ordinary person.Note: During September, 6 as the daily maximum UV index converts into the following advice:
Adhere to precautions and respect sun safety doctrines. Avoiding sunburn is vital. Avoid direct Sun exposure and seek shade between 10 a.m. and 4 p.m., when UV radiation is at its peak, but keep in mind that not all shade structures provide complete protection. Experience reduced UV exposure by about half when donning a wide-brim hat. Attention! The combination of sand and water reflections enhances UV ray intensity.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Charleston, SC
- Average high temperature in September: 83.5°F
The warmest month (with the highest average high temperature) is July (88.2°F).
The month with the lowest average high temperature is January (57°F).
- Average low temperature in September: 73°F
The month with the highest average low temperature is July (77.4°F).
The coldest month (with the lowest average low temperature) is January (44.4°F).
Average pressure in September
Charleston, 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
Charleston, SC
- Average wind speed in September: 8.3mph
The windiest month (with the highest average wind speed) is April (9.4mph).
The calmest month (with the lowest average wind speed) is August (7.5mph).
Average humidity in September
Charleston, SC
- Average humidity in September: 75%
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
Charleston, SC
- Average rainfall in September: 5"
The wettest month (with the highest rainfall) is August (7.13").
The driest month (with the least rainfall) is January (1.42").
Average rainfall days in September
Charleston, SC
- Average rainfall days in September: 18.4 days
The month with the highest number of rainy days is August (24.8 days).
The month with the least rainy days is November (8.7 days).
Average snowfall in September
Charleston, SC
- Average snowfall in September: 0"
The month with the highest snowfall is January (0.12").
The months with the least snowfall are February, March, April, May, June, July, August, September, October and November (0").
Average snowfall days in September
Charleston, SC
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (0.4 days).
The months with the least snowfall days are March, April, May, June, July, August, September, October and November (0 days).
Average sea temperature in September
Charleston, SC
- Average sea temperature in September: 81.7°F
The best month for swimming (with the highest average sea temperature) is August (83.5°F).
The coldest month (with the lowest average sea temperature) is February (61.9°F).
Average daylight in September /
Average sunshine in September
Charleston, 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: 9h and 6min
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
Charleston, SC
- Average sunshine days in September: 8.5 days
The month with the most sunshine days is January (19.3 days).
The month with the least sunshine days is August (3.8 days).
Average UV index in September
Charleston, 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
Charleston, SC
- Average cloud cover in September: 29
The months with the most cloud cover are February and December (Cloud cover 39).
The months with the least cloud cover are June and July (Cloud cover 26).
Average visibility in September
Charleston, 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).
