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September Weather in Knoxville, United States

Last updated: June 24, 2025

In September, the average temperature in Knoxville, United States hovers around 17°C (62°F), with a minimum dropping to 0°C (33°F) and a maximum soaring to 31°C (88°F). You can expect approximately 89 mm (3.5 in) of precipitation over 8 days, alongside an average humidity of 67%.

September Temperature in Knoxville

In September in Knoxville, the average temperature is 17°C (62°F). Maximums can reach 31°C (88°F) and minimums can be as low as 0°C (33°F). It's a great time to explore Knoxville, so be prepared for both warm days and cooler evenings!

September Weather in Knoxville: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Knoxville, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Knoxville, September typically has an average temperature of 17°C (62°F), with highs reaching up to 31°C (88°F) and lows dropping to around 0°C (33°F).
JanFebMarAprMayJunJulAugSepOctNovDec252834455765716962523731
Data source: Temperature data for Knoxville generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Knoxville

In Knoxville in September, the precipitation amount is 89 mm (3.5 in) over a span of 8 days.

September Precipitation Trends in Knoxville

The chart displays monthly precipitation patterns in Knoxville, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Knoxville, September typically receives around 89 mm (3.5 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec6784751091169512479891197880
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Knoxville

In Knoxville in September, humidity is 67%. With an average temperature of 17°C (62°F), this humidity feels like a warm embrace, making travel enjoyable as long as you stay hydrated and take breaks in shaded areas.

September Average Humidity in Knoxville

This chart illustrates the average monthly humidity levels in Knoxville, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Knoxville is approximately 67%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%90%89%88%80%79%74%64%67%81%89%88%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Knoxville

In Knoxville in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Knoxville.

Maximum UV Index Levels in Knoxville for September

The chart shows the monthly maximum UV Index (UVI) for Knoxville in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Knoxville typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Knoxville September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Knoxville Compares to Other Months

Weather in Knoxville varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Knoxville, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Knoxville, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-4°C (25°F)67 mm (2.6 inches)89%moderate
February Weather-2°C (28°F)84 mm (3.3 inches)90%moderate
March Weather1°C (35°F)75 mm (2.9 inches)89%high
April Weather7°C (46°F)109 mm (4.3 inches)88%very high
May Weather14°C (57°F)116 mm (4.6 inches)80%very high
June Weather19°C (66°F)95 mm (3.7 inches)79%very high
July Weather21°C (71°F)124 mm (4.9 inches)74%very high
August Weather20°C (69°F)79 mm (3.1 inches)64%very high
September Weather17°C (62°F)89 mm (3.5 inches)67%very high
October Weather11°C (52°F)119 mm (4.7 inches)81%high
November Weather3°C (38°F)78 mm (3.1 inches)89%moderate
December Weather-1°C (31°F)80 mm (3.2 inches)88%low

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