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September Weather in Louisville, United States

Last updated: June 24, 2025

In Louisville, United States, the average temperature in September hovers around 23°C (73°F). However, be prepared for a range: temperatures can dip to a chilly 8°C (47°F) or soar to a sizzling 36°C (97°F). During this time, expect about 90 mm (3.6 in) of precipitation spread over 10 days, accompanied by an average humidity level of 76%. Be ready for a mixed bag of weather!

September Temperature in Louisville

In September in Louisville, the average temperature is 23°C (73°F). The maximum can reach 36°C (97°F) and the minimum can be as low as 8°C (47°F). This variety in temperatures makes Louisville a great destination for travelers seeking both warm days and cooler nights.

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

The chart illustrates September temperature patterns in Louisville, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Louisville, September typically has an average temperature of 23°C (73°F), with highs reaching up to 36°C (97°F) and lows dropping to around 8°C (47°F).
JanFebMarAprMayJunJulAugSepOctNovDec414752596975797773634945
Data source: Temperature data for Louisville 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 Louisville

In Louisville in September, the precipitation amount is 90 mm (3.6 in) spread over the course of 10 days.

September Precipitation Trends in Louisville

The chart displays monthly precipitation patterns in Louisville, 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 Louisville, September typically receives around 90 mm (3.6 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec1011661611331131031041199112283135
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Louisville

In Louisville in September humidity is 76%. With an average temperature of 23°C (73°F), this humidity feels like a warm, enveloping blanket, making outdoor activities feel more intense and prompting travelers to seek shade or cool breaks more frequently.

September Average Humidity in Louisville

This chart illustrates the average monthly humidity levels in Louisville, 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 Louisville is approximately 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%86%82%85%85%83%76%76%80%88%88%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Louisville

In Louisville in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Louisville.

Maximum UV Index Levels in Louisville for September

The chart shows the monthly maximum UV Index (UVI) for Louisville 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 Louisville typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46810111111109763
Data source: Louisville 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 Louisville Compares to Other Months

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

This table compares monthly weather conditions in Louisville, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (42°F)101 mm (4.0 inches)86%moderate
February Weather8°C (47°F)166 mm (6.5 inches)86%high
March Weather11°C (53°F)161 mm (6.3 inches)86%very high
April Weather15°C (59°F)133 mm (5.2 inches)82%very high
May Weather20°C (69°F)113 mm (4.5 inches)85%extreme
June Weather24°C (75°F)102 mm (4.0 inches)85%extreme
July Weather26°C (79°F)104 mm (4.1 inches)83%extreme
August Weather25°C (77°F)119 mm (4.7 inches)76%very high
September Weather23°C (73°F)90 mm (3.6 inches)76%very high
October Weather17°C (63°F)122 mm (4.8 inches)80%high
November Weather9°C (49°F)83 mm (3.3 inches)88%high
December Weather7°C (45°F)135 mm (5.3 inches)88%moderate

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