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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 20°C (68°F). You can expect a minimum dip to 4°C (39°F) and a maximum rise to 33°C (93°F). Be prepared for 108 mm (4.2 in) of precipitation spread over 9 days, contributing to an average humidity of 77%.

September Temperature in Louisville

In September in Louisville, the average temperature is 20°C (68°F). Maximum temperatures can reach up to 33°C (93°F), while minimum temperatures can drop as low as 4°C (39°F). This range makes it an ideal time for travelers to explore the area's outdoor attractions while being prepared for both warm and cooler moments.

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 20°C (68°F), with highs reaching up to 33°C (93°F) and lows dropping to around 4°C (39°F).
JanFebMarAprMayJunJulAugSepOctNovDec303340506270757267574135
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 108 mm (4.2 in) spread over 9 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 108 mm (4.2 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec90104101134119128126961081109393
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 77%. With an average temperature of 20°C (68°F), this humidity feels like a warm, sticky embrace, making it essential for travelers to stay hydrated and take breaks in shaded areas to avoid feeling sluggish in the heat.

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 77%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%88%87%87%81%83%82%76%77%82%89%86%
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.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
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-1°C (30°F)90 mm (3.5 inches)88%moderate
February Weather1°C (33°F)104 mm (4.1 inches)88%moderate
March Weather5°C (41°F)101 mm (4.0 inches)87%high
April Weather10°C (51°F)134 mm (5.3 inches)87%very high
May Weather17°C (62°F)119 mm (4.7 inches)81%very high
June Weather21°C (70°F)128 mm (5.0 inches)83%very high
July Weather24°C (75°F)126 mm (5.0 inches)82%very high
August Weather22°C (73°F)96 mm (3.8 inches)76%very high
September Weather20°C (68°F)108 mm (4.2 inches)77%very high
October Weather14°C (57°F)110 mm (4.3 inches)82%high
November Weather5°C (41°F)93 mm (3.7 inches)89%moderate
December Weather2°C (35°F)93 mm (3.7 inches)86%low

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