September weather forecastKnoxville, TN
September
Weather in September
September in Knoxville welcomes fall with open arms, marking a significant drop in temperatures compared to August. Though there is an increase in rainfall, it is the month with the least rainfall overall, averaging just 1.5" (38mm). As the intense summer heat fades, the city indulges in crisp autumn weather. The city transitions kindly with hues of falling leaves and warm hues, making September in Knoxville a scenic pleasure for locals and visitors alike.Temperature
With the onset of September, the average high-temperature in Knoxville subtly recedes from August's tropical 88.2°F (31.2°C) to a moderately hot 82.2°F (27.9°C). Despite the intense daytime heat, Knoxville sustains a steady low-temperature average of 59.9°F (15.5°C) during September.Heat index
In September, the heat index is computed to be a hot 87.8°F (31°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.The standards for the heat index are set for locations in shade and under light breezes. Exposure to the sun directly might heighten the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'feels like', is the outcome of merging air's temperature and its humidity metrics. Elements of metabolic variation, physical activity, and clothing contribute to the effect of temperature on an individual. Should you be directly under the sun, anticipate a possible increase in the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely vital to babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
Humidity
In Knoxville, the average relative humidity in September is 72%.Rainfall
September is the month with the least rainfall. Rain falls for 11.3 days and accumulates 1.5" (38mm) of precipitation.Snowfall
May through October are months without snowfall.Daylight
In Knoxville, the average length of the day in September is 12h and 23min.On the first day of September, sunrise is at 7:08 am and sunset at 8:02 pm. On the last day of the month, sunrise is at 7:30 am and sunset at 7:20 pm EDT.
Sunshine
The average sunshine in September is 8.6h.UV index
The average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for the average person.Note: The maximum daily UV index of 5 in September converts into the following recommendations:
Safety measures are advised. Light-skinned individuals may experience burns in under half an hour. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Knoxville, TN
- Average high temperature in September: 82.2°F
The warmest month (with the highest average high temperature) is July (88.9°F).
The month with the lowest average high temperature is January (44.8°F).
- Average low temperature in September: 59.9°F
The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (29.3°F).
Average pressure in September
Knoxville, TN
- Average pressure in September: 30.04"Hg
The months with the highest atmospheric pressure are January and November (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.98"Hg).
Average wind speed in September
Knoxville, TN
- Average wind speed in September: 4mph
The windiest month (with the highest average wind speed) is April (6mph).
The calmest month (with the lowest average wind speed) is August (3.8mph).
Average humidity in September
Knoxville, TN
- Average humidity in September: 72%
The months with the highest relative humidity are February and December (78%).
The month with the lowest relative humidity is August (70%).
Average rainfall in September
Knoxville, TN
- Average rainfall in September: 1.5"
The wettest month (with the highest rainfall) is February (3.66").
The driest month (with the least rainfall) is September (1.5").
Average rainfall days in September
Knoxville, TN
- Average rainfall days in September: 11.3 days
The month with the highest number of rainy days is July (16.2 days).
The month with the least rainy days is November (8.4 days).
Average snowfall in September
Knoxville, TN
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.57").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Knoxville, TN
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (3.8 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Knoxville, TN
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 36min).
The month with the shortest days is December (Average daylight: 9h and 48min).
- Average sunshine in September: 8h and 36min
The month with the most sunshine is June (Average sunshine: 10h and 36min).
The month with the least sunshine is January (Average sunshine: 4h and 54min).
Average sunshine days in September
Knoxville, TN
- Average sunshine days in September: 17.4 days
The month with the most sunshine days is October (20.5 days).
The month with the least sunshine days is July (12.9 days).
Average UV index in September
Knoxville, TN
- Average UV index in September: 5
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February and December (UV index 2).
Average cloud cover in September
Knoxville, TN
- Average cloud cover in September: 30
The month with the most cloud cover is February (Cloud cover 54).
The month with the least cloud cover is June (Cloud cover 28).
Average visibility in September
Knoxville, TN
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is January (5mi).
