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
With the transition into September, Williams notes an average high-temperature of a warm 85.6°F (29.8°C), closely resembling August. During the month of September, Williams anticipates a mean low-temperature of 68.5°F (20.3°C).Heat index
In September, the heat index is estimated at a sweltering 96.8°F (36°C). Adopt heightened safety measures, heat cramps and heat exhaustion may occur. Sustained activity might cause heatstroke.Be advised, the heat index considers values for conditions in shade and with a light breeze. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', evaluates the perceived heat by adding the effect of moisture in the air. The influence of weather is personal, with a diverse population experiencing it differently due to differences in body mass, stature, and degree of activity. Given the impact of direct sunlight, it's noteworthy that the felt temperature can rise by 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely vital to babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it's vital to remain hydrated, particularly during prolonged physical activities.
The human body cools itself through perspiration, as excessive warmth is removed from the body through sweat evaporation. Elevated relative humidity diminishes evaporation, thereby reducing the body's ability to shed heat and creating a feeling of being too warm. Heat-related challenges, like dehydration, can be anticipated when body heat isn't managed effectively.
Humidity
In Williams, the average relative humidity in September is 76%.Rainfall
In September, the rain falls for 14.2 days. Throughout September, 1.89" (48mm) of precipitation is accumulated. In Williams, during the entire year, the rain falls for 149.7 days and collects up to 21.5" (546mm) of precipitation.Snowfall
March through December are months without snowfall.Daylight
In September, the average length of the day is 12h and 22min.On the first day of the month, sunrise is at 6:58 am and sunset at 7:47 pm. On the last day of September, sunrise is at 7:17 am and sunset at 7:08 pm EDT.
Sunshine
The average sunshine in September in Williams is 8.7h.UV index
In September, the average daily maximum UV index is 6. A UV Index value of 6 to 7 symbolizes a high health vulnerability from exposure to the Sun's UV radiation for the average person.Note: A daily maximum UV index of 6 in September translates into the following instructions:
Refrain from overexposure. Fair-skinned individuals could burn in under 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. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.
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?
What is the average length of the day in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Williams have in September?
What is the UV index intensity in September?
Average temperature in September
Williams, SC
- Average high temperature in September: 85.6°F
The warmest month (with the highest average high temperature) is July (91.8°F).
The month with the lowest average high temperature is January (56.1°F).
- Average low temperature in September: 68.5°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 (39.9°F).
Average pressure in September
Williams, 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
Williams, SC
- Average wind speed in September: 5.3mph
The windiest month (with the highest average wind speed) is April (6.7mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in September
Williams, SC
- Average humidity in September: 76%
The months with the highest relative humidity are August and December (77%).
The months with the lowest relative humidity are January, March and November (72%).
Average rainfall in September
Williams, SC
- Average rainfall in September: 1.89"
The wettest month (with the highest rainfall) is August (3.15").
The driest month (with the least rainfall) is November (0.75").
Average rainfall days in September
Williams, SC
- Average rainfall days in September: 14.2 days
The month with the highest number of rainy days is July (21.1 days).
The month with the least rainy days is November (6.2 days).
Average snowfall in September
Williams, SC
- Average snowfall in September: 0"
The months with the highest snowfall are January and 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
Williams, 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 April, May, June, July, August, September, October and November (0 days).
Average daylight in September /
Average sunshine in September
Williams, 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 4min
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 30min).
Average sunshine days in September
Williams, SC
- Average sunshine days in September: 13.5 days
The month with the most sunshine days is November (21.1 days).
The month with the least sunshine days is July (6.9 days).
Average UV index in September
Williams, 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
Williams, SC
- Average cloud cover in September: 31
The month with the most cloud cover is December (Cloud cover 42).
The months with the least cloud cover are July and October (Cloud cover 29).
Average visibility in September
Williams, SC
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).
Williams, South Carolina, USA
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