September Weather in Louisville, United States

Last updated: June 24, 2025

In September, the average temperature in Louisville, United States hovers around 16°C (61°F). Be prepared for temperature fluctuations, as it can dip to a chilly -4°C (25°F) or soar to a warm 33°C (92°F). The area receives about 42 mm (1.6 in) of precipitation over 8 days, making it essential to carry an umbrella. With an average humidity of 65%, it's a month where mild weather meets occasional rain—perfect for enjoying the local scenery!

September Temperature in Louisville

In September in Louisville, the average temperature is 16°C (61°F). The maximum can reach 33°C (92°F) and the minimum can be as low as -4°C (25°F). Be sure to pack a variety of clothing to enjoy both warm days and cooler nights during your travels.

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 16°C (61°F), with highs reaching up to 33°C (92°F) and lows dropping to around -4°C (25°F).

Data source: Temperature data for Louisville generated using information from the Copernicus Climate Change Service.

September Precipitation in Louisville

In Louisville in September, the precipitation amount is 42 mm (1.6 in) over a span 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 42 mm (1.6 inches) of precipitation spread over approximately 8 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Louisville

In Louisville in September, humidity is 65%. With an average temperature of 16°C (61°F), this humidity feels like a gentle warmth enveloping you, making it ideal for exploring the sights without overwhelming discomfort.

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 65%, offering insight into how humid the weather typically is during this month.

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 reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more 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 10, which falls under the very high exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	-3°C (26°F)	25 mm (1.0 inches)	88%	moderate
February Weather	-4°C (26°F)	36 mm (1.4 inches)	87%	high
March Weather	2°C (35°F)	62 mm (2.5 inches)	81%	very high
April Weather	5°C (42°F)	68 mm (2.7 inches)	76%	extreme
May Weather	10°C (50°F)	134 mm (5.3 inches)	66%	extreme
June Weather	17°C (63°F)	74 mm (2.9 inches)	58%	extreme
July Weather	20°C (68°F)	71 mm (2.8 inches)	52%	extreme
August Weather	19°C (67°F)	67 mm (2.7 inches)	56%	extreme
September Weather	16°C (61°F)	42 mm (1.6 inches)	65%	very high
October Weather	7°C (45°F)	48 mm (1.9 inches)	76%	high
November Weather	2°C (36°F)	30 mm (1.2 inches)	82%	moderate
December Weather	-2°C (29°F)	19 mm (0.8 inches)	89%	moderate