Knoxville, TN weather in September
In September, Knoxville sees highs around 83°F and lows around 59°F: warm and often humid, with some rain. There are about 9 days with rain.
- Normal high
- 83°F
- Normal low
- 59°F
- Wet days
- 9
- 4.1 in total
- Muggy days
- 9
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 87°F | 78°F |
| Normal low | 63°F | 53°F |
| Chance of a wet day | 28% | 27% |
| Sunrise / sunset | 7:07 am / 8:03 pm | 7:30 am / 7:21 pm |
| Daylight | 12.9 h | 11.9 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Eastern Time).
A typical September day
- 6 am63°Fdew point 60°F
- 9 am69°Fdew point 62°F
- Noon77°Fdew point 61°F
- 3 pm81°Fdew point 60°F
- 6 pm78°Fdew point 60°F
- 9 pm71°Fdew point 61°F
NOAA hourly normals (local standard time) from Knoxville Mcghee Tyson Airport (11 mi away); average wind 5 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F6 of 30
- Hot dayshigh 90°F or more5 of 30
- Muggy daysdaily mean dew point 65°F or more9 of 30
- Wet daysat least 0.01 in of rain or melted snow9 of 30
- Notable rainat least 0.10 in6 of 30
- Freezing nightslow 32°F or below0 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 4.1 in; a dry September brings about 2.1 in and a wet one about 5.6 in (25th and 75th percentiles). About 3 days bring half an inch or more, and about 1 an inch or more.
How September varies from year to year
- Warmest September, 1991-20202016: average high 91°F
- Coolest September2006: average high 78°F
- Wettest September2006: 9.9 in
- Driest September2019: 0.2 in
- Highest reading97°F (September 4, 2011)
- Lowest reading37°F (September 30, 1993)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 88°F | 83°F | 72°F |
| Normal low | 65°F | 59°F | 46°F |
| Wet days | 10 | 9 | 8 |
| Comfortable days | 0 | 6 | 18 |
| Daylight | 13.5 h | 12.4 h | 11.3 h |
Highs change by -5°F from August and -11°F into October.
Nearby alternatives in September
- Warmer: Columbia, SC212 mi · high 89°F · 8 wet days
- Cooler: Gatlinburg, TN29 mi · high 78°F · 11 wet days
How Knoxville ranks in September
- Normal high169th warmest of 378 cities; 6th of 7 in Tennessee
- Wet days218th driest of 378
- Comfortable days193rd most of 342
What to pack for Knoxville in September
- A rain jacket or umbrella – rain on about 9 days
Heating and cooling
September has 23 heating degree days and 196 cooling degree days (base 65°F), 4% of the year's total heating and cooling demand.
Questions
How hot is Knoxville in September?
The normal high is 83°F and the normal low is 59°F. From 1991 to 2020 the hottest September reading was 97°F (most recently on September 4, 2011).
Does it rain a lot in Knoxville in September?
About 9 days in September have at least 0.01 in of precipitation, and the normal total is 4.1 in. The wettest September in 1991-2020 was in 2006 (9.9 in); the driest was in 2019 (0.2 in).
Is September a good time to visit Knoxville?
September ranks 6th of 12 months on our comfort score for Knoxville (53 out of 100). It has about 6 comfortable days and about 5 days at 90°F or hotter. The best months are April and October.
Where the numbers come from
- Temperature, rain and frost dates: Knoxville Exp Stn (USC00404946), 4.8 mi SSW of the city center, 830 ft (69 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Snowfall, snow depth and humidity and wind by hour: Knoxville Mcghee Tyson Airport (USW00013891), 11 mi SSW of the city center, 962 ft (63 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Mc Ghee Tyson Airport (723260-13891), 11 mi SSW of the city center, 970 ft (71 ft higher than the city). Hourly observations, 1991-2020.
- Not available for this location: cloud cover (no station close enough or similar enough in elevation).