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 onset of September, a modest change to a warm 84.7°F (29.3°C) from August's 90°F (32.2°C) is noted in high-temperature. Throughout the September nights, Irmo encounters a low-temperature of 66.6°F (19.2°C).Heat index
September's heat index is evaluated at a tropical 93.2°F (34°C). Ensure heightened precautions, risk of heat cramps and heat exhaustion is significant. Sustained activity could provoke heatstroke.Remember that heat index calculations are made for conditions in the shade with light wind. A rise in the heat index by 15 Fahrenheit (8 Celsius) degrees may result from direct sunlight exposure.
Note: The heat index, also known as 'real feel' or 'apparent temperature', measures the perceived warmth when incorporating the humidity present in the air. Elements such as metabolic variations, pregnancy, and physical exertion can shape one's weather perception. Exposure to direct sun rays can influence the heat you feel, pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values are of high significance for children. Young ones often underestimate the need for rest and rehydration. Thirst appears late in dehydration - hence, it is important to keep hydrated, particularly during prolonged physical activities.
Humidity
In Irmo, the average relative humidity in September is 72%.Rainfall
The month with the least rainfall is September, when the rain falls for 12 days and typically collects 1.54" (39mm) of precipitation.Snowfall
In Irmo, snow does not fall in April through November.Daylight
The average length of the day in September is 12h and 22min.On the first day of the month, sunrise is at 6:58 am and sunset at 7:50 pm. On the last day of September, sunrise is at 7:19 am and sunset at 7:09 pm EDT.
Sunshine
In September, the average sunshine in Irmo is 8.6h.UV index
The average daily maximum UV index in September is 6. A UV Index estimate of 6 to 7 represents a high health vulnerability from unsafe exposure to UV radiation for the ordinary person.Note: A maximum high daily UV index of 6 during September translates into the following directions:
Shield from overexposure. Defense against sun-related harm is required. The Sun's UV radiation is most potent between the hours of 10 a.m. and 4 p.m. Try to avoid direct sunlight during this time. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot is September?
What is the average humidity in September?
What is the driest month?
How many days does it rain in September?
When it does not snow?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Irmo have in September?
How high is the UV index in September?
Average temperature in September
Irmo, SC
- Average high temperature in September: 84.7°F
The warmest month (with the highest average high temperature) is July (91.4°F).
The month with the lowest average high temperature is January (52.3°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 (36.9°F).
Average pressure in September
Irmo, SC
- Average pressure in September: 30.02"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
Irmo, SC
- Average wind speed in September: 5.8mph
The windiest month (with the highest average wind speed) is April (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).
Average humidity in September
Irmo, SC
- Average humidity in September: 72%
The month with the highest relative humidity is December (75%).
The month with the lowest relative humidity is July (70%).
Average rainfall in September
Irmo, SC
- Average rainfall in September: 1.54"
The wettest month (with the highest rainfall) is December (3.11").
The driest month (with the least rainfall) is September (1.54").
Average rainfall days in September
Irmo, SC
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is July (17.4 days).
The month with the least rainy days is October (7.8 days).
Average snowfall in September
Irmo, SC
- Average snowfall in September: 0"
The month with the highest snowfall is February (0.43").
The months with the least snowfall are April, May, June, July, August, September, October and November (0").
Average snowfall days in September
Irmo, SC
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (0.5 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
Irmo, 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 54min).
The month with the least sunshine is December (Average sunshine: 5h and 30min).
Average sunshine days in September
Irmo, SC
- Average sunshine days in September: 15.9 days
The month with the most sunshine days is October (21.8 days).
The month with the least sunshine days is July (10.8 days).
Average UV index in September
Irmo, SC
- Average UV index in September: 6
The months with the highest UV index are June and July (UV index 7).
The month with the lowest UV index is January (UV index 2).
Average cloud cover in September
Irmo, SC
- Average cloud cover in September: 31
The months with the most cloud cover are February and December (Cloud cover 41).
The months with the least cloud cover are June and October (Cloud cover 28).
Average visibility in September
Irmo, 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).
Irmo, South Carolina, USA
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