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September Weather in Louisville, United States

Last updated: June 24, 2025

In Louisville, United States, the average temperature in September is a comfortable 21°C (70°F), with minimums dipping to 5°C (42°F) and potential maximums soaring up to 36°C (97°F). Prepare for some moisture, as the area receives around 88 mm (3.5 in) of precipitation over 8 days, and anticipate a relative humidity of 75%.

September Temperature in Louisville

In September in Louisville, the average temperature is 21°C (70°F). Maximum temperatures can reach 36°C (97°F), while the minimum can drop as low as 5°C (42°F). Travelers should be prepared for a wide range of weather conditions, ensuring they pack both warm and light clothing.

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 21°C (70°F), with highs reaching up to 36°C (97°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec262642516377787570534132
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 88 mm (3.5 in) over the course of 8 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 88 mm (3.5 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec333099521391218992881313037
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 75%. With an average temperature of 21°C (70°F), this humidity feels like a warm, enveloping blanket that makes exploring the area feel slightly sticky, requiring travelers to stay hydrated and take occasional breaks in the shade to fully enjoy their adventures.

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 75%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%80%73%75%78%82%83%81%75%75%82%83%
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 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 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 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356810101098642
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 Weather-3°C (26°F)33 mm (1.3 inches)76%moderate
February Weather-3°C (26°F)30 mm (1.2 inches)80%moderate
March Weather5°C (42°F)99 mm (3.9 inches)73%high
April Weather10°C (51°F)52 mm (2.0 inches)74%very high
May Weather17°C (64°F)139 mm (5.5 inches)78%very high
June Weather25°C (77°F)121 mm (4.8 inches)82%very high
July Weather26°C (79°F)89 mm (3.5 inches)83%very high
August Weather24°C (75°F)92 mm (3.6 inches)80%very high
September Weather21°C (70°F)88 mm (3.5 inches)75%very high
October Weather12°C (53°F)131 mm (5.2 inches)75%high
November Weather5°C (41°F)30 mm (1.2 inches)82%moderate
December Weather0°C (32°F)37 mm (1.5 inches)83%low

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