September weather forecast
Sumter, SC

Weather in September

September, the first month of the autumn in Sumter, is also a moderately hot month, with an average temperature fluctuating between 66.6°F (19.2°C) and 83.7°F (28.7°C).

Temperature

In September, the average high-temperature is relatively the same as in August - a warm 83.7°F (28.7°C). The average low-temperature, in September, is 66.6°F (19.2°C).

Heat index

The average heat index in September is appraised at a hot 91.4°F (33°C). Take extra precautions, as heat cramps and heat exhaustion are possible. Sustained activity may result in heatstroke.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature', 'felt air temperature', 'feels like', or 'real feel', is calculated by taking the relative humidity value for a specific location and factoring it into the air temperature reading. Additional factors like activity, differences in body mass, height, and shape, wind, and clothing affect individual temperature impact. Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

The average relative humidity in September is 75%.

Rainfall

In September, in Sumter, the rain falls for 14.1 days. Throughout September, 2.48" (63mm) of precipitation is accumulated. In Sumter, during the entire year, the rain falls for 161.8 days and collects up to 33.35" (847mm) of precipitation.

Snowfall

April through October are months without snowfall in Sumter, South Carolina.

Daylight

In Sumter, the average length of the day in September is 12h and 22min.
On the first day of September, sunrise is at 6:55 am and sunset at 7:47 pm. On the last day of the month, sunrise is at 7:15 am and sunset at 7:07 pm EDT.

Sunshine

In September, the average sunshine is 8.7h.

UV index

In September, the average daily maximum UV index is 6. A UV Index reading of 6 to 7 represents a high health risk from exposure to the Sun's UV rays for ordinary individuals.
Note: In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions against overexposure. Fair-skinned people may get burned in less than 20 minutes. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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FAQ

What is the temperature in September in Sumter?

In September, in Sumter, the average high-temperature is 83.7°F (28.7°C), and the average low-temperature is 66.6°F (19.2°C). The average heat index (a.k.a. 'felt air temperature', 'real feel'), which combines relative humidity and air temperature, in September is appraised at 91.4°F (33°C).

What is the average humidity in September in Sumter?

In Sumter, the average relative humidity in September is 75%.

How many days does it rain in September in Sumter?

In Sumter, during September, the rain falls for 14.1 days and regularly aggregates up to 2.48" (63mm) of precipitation.

When it does not snow in Sumter?

April through October are months without snowfall in Sumter, South Carolina.

How many hours of daylight does Sumter have in September?

In Sumter, the average day length in September is 12h and 22min.

When is the sunrise / sunset in September in Sumter?

On the first day of September, sunrise is at 6:55 am and sunset at 7:47 pm. On the last day of the month, sunrise is at 7:15 am and sunset at 7:07 pm EDT.

How many hours of sunshine does Sumter have in September?

The average sunshine duration in September is 8.7h.

How high is the UV index in September in Sumter?

In September, the average daily maximum UV index in Sumter is 6. A UV Index estimate of 6 to 7 represents a high health threat from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Sumter, SC

Average temperature in September - Sumter, SC
  • Average high temperature in September: 83.7°F

The warmest month (with the highest average high temperature) is July (90.7°F).
The month with the lowest average high temperature is January (52.9°F).

  • Average low temperature in September: 66.6°F

The month with the highest average low temperature is July (72.9°F).
The coldest month (with the lowest average low temperature) is January (38.1°F).

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Average pressure in September
Sumter, SC

Average pressure in September - Sumter, 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).

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Average wind speed in September
Sumter, SC

Average wind speed in September - Sumter, SC
  • Average wind speed in September: 6.3mph

The windiest months (with the highest average wind speed) are February and April (8.5mph).
The calmest month (with the lowest average wind speed) is August (5.6mph).

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Average humidity in September
Sumter, SC

Average humidity in September - Sumter, SC
  • Average humidity in September: 75%

The month with the highest relative humidity is May (76%).
The months with the lowest relative humidity are January and November (70%).

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Average rainfall in September
Sumter, SC

Average rainfall in September - Sumter, SC
  • Average rainfall in September: 2.48"

The wettest month (with the highest rainfall) is December (3.58").
The driest month (with the least rainfall) is January (1.89").

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Average rainfall days in September
Sumter, SC

Average rainfall days in September - Sumter, SC
  • Average rainfall days in September: 14.1 days

The month with the highest number of rainy days is July (20.1 days).
The month with the least rainy days is October (8.5 days).

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Average snowfall in September
Sumter, SC

Average snowfall in September - Sumter, SC
  • Average snowfall in September: 0"

The month with the highest snowfall is February (0.55").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in September
Sumter, SC

Average snowfall days in September - Sumter, SC
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (0.6 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).

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Average daylight in September /
Average sunshine in September
Sumter, SC

Average daylight in September / Average sunshine in September - Sumter, SC
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).

  • Average sunshine in September: 8h and 4min

The month with the most sunshine is July (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 5h and 18min).

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Average sunshine days in September
Sumter, SC

Average sunshine days in September - Sumter, SC
  • Average sunshine days in September: 13.5 days

The month with the most sunshine days is October (20.8 days).
The month with the least sunshine days is July (8.8 days).

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Average UV index in September
Sumter, SC

Average UV index in September - Sumter, 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, February and December (UV index 3).

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Average cloud cover in September
Sumter, SC

Average cloud cover in September - Sumter, SC
  • Average cloud cover in September: 33

The months with the most cloud cover are February and December (Cloud cover 42).
The month with the least cloud cover is October (Cloud cover 29).

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Average visibility in September
Sumter, SC

Average visibility in September - Sumter, 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).

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