Louisville
Kentucky, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Louisville, KY

A distant view of the Louisville city, Kentucky, from across the bridge, at dusk, reflected in the water below
A distant view of the Louisville city, Kentucky, from across the bridge, at dusk, reflected in the water below
September, the first month of the autumn, in Louisville, is still a warm month, with average temperature ranging between max 81.5°F (27.5°C) and min 60.4°F (15.8°C).

Temperature

In September, the average high-temperature slightly decreases, from a tropical 88.3°F (31.3°C) in August, to a warm 81.5°F (27.5°C). In September, in Louisville, the average low-temperature is 60.4°F (15.8°C).

Heat index

In September, the average heat index is appraised at a tropical 86°F (30°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature', 'feels like', 'real feel', or 'felt air temperature', is a measure of how hot it feels when the actual air humidity is factored in. Additional factors like differences in body mass, height, and shape, metabolic differences, clothing, and activity influence one's weather impression. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.

Humidity

With an average relative humidity of 72.9%, September is the most humid month in Louisville.

Rainfall

The month with the least rainfall is September when the rain falls for 8 days and typically collects 3.1" (77.5mm) of precipitation.

Snowfall

May through September are months without snowfall.

Daylight

In Louisville, the average length of the day is 12.4h.

Sunshine

In September, the average sunshine in Louisville, Kentucky, is 7.8h.

UV index

In September, the average daily maximum UV index is 7. A UV Index of 6 to 7 symbolizes a high threat to health from unsafe exposure to the UV radiation for the average person.
Note: The average daily UV index of 7 in September transform into the following instructions:
Take precautions against overexposure. Protection against sun damage is needed. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.

What is the temperature in September in Louisville?

In Louisville, Kentucky, in September, the average high-temperature is 81.5°F (27.5°C), and the average low-temperature is 60.4°F (15.8°C). The average heat index (a.k.a. 'apparent temperature', 'real feel'), that combines relative humidity and air temperature, in September is evaluated at 86°F (30°C).

What is the most humid month in Louisville?

The most humid month in Louisville is September, with an average relative humidity of 72.9%.

What is the average humidity in September in Louisville?

In Louisville, Kentucky, the average relative humidity in September is 72.9%.

How many days does it rain in September in Louisville?

In Louisville, in September, during 8 rainfall days, 3.1" (77.5mm) of precipitation is typically accumulated.

What is the driest month in Louisville?

September is the month with the least rainfall in Louisville. Rain falls for 8 days and accumulates 3.1" (77.5mm) of precipitation.

Does it snow in Louisville in September?

In Louisville, in September, it doesn't snow. In October, it regularly snows.

When it does not snow in Louisville?

In Louisville, Kentucky, snow does not fall in May through September.

What is the average length of the day in September in Louisville?

In September, the average length of the day in Louisville is 12.4h.

How long on average sun shines in September in Louisville?

The average sunshine in September in Louisville, Kentucky, is 7.8h.

How high is the UV index in September in Louisville?

The average daily maximum UV index in September in Louisville, Kentucky, is 7. A UV Index estimate of 6 to 7 represents a high health threat from the exposure to the Sun's UV radiation.
Average temperature in September - Louisville, KY
  • Average high temperature in September: 81.5°F

The warmest month (with the highest average high temperature) is July (88.7°F).
The month with the lowest average high temperature is January (43°F).

  • Average low temperature in September: 60.5°F

The month with the highest average low temperature is July (69.9°F).
The coldest month (with the lowest average low temperature) is January (26.8°F).

Average humidity in September - Louisville, KY
  • Average humidity in September: 72.9%

The month with the highest relative humidity is September (72.9%).
The month with the lowest relative humidity is April (61.5%).

Average rainfall in September - Louisville, KY
  • Average rainfall in September: 3.1"

The wettest month (with the highest rainfall) is May (5.3").
The driest month (with the lowest rainfall) is September (3.1").

Average rainfall days in September - Louisville, KY
  • Average rainfall days in September: 8 days

The month with the highest number of rainy days is May (12.6 days).
The month with the lowest number of rainy days is October (7.7 days).

Average snowfall in September - Louisville, KY
  • Average snowfall in September: 0"

The month with the highest snowfall is February (4.5").
Months with the lowest snowfall are May, June, July, August and September (0").

Average snowfall days in September - Louisville, KY
  • Average snowfall days in September: 0 days

Months with the highest number of snowfall days are January and February (3.6 days).
Months with the lowest number of snowfall days are May, June, July, August and September (0 days).

Average daylight in September / Average sunshine in September - Louisville, KY
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.8h).
The month with shortest days is December (Average daylight: 9.5h).

  • Average sunshine in September: 7.8h

The month with most sunshine is June (Average sunshine: 9.6h).
The month with least sunshine is December (Average sunshine: 3.8h).

Average UV index in September - Louisville, KY
  • Average UV index in September: 7

Months with the highest UV index are June, July and August (UV index 9).
Months with the lowest UV index are January and December (UV index 2).