St. Louis
Missouri, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
St. Louis, MO

A beautiful twilight view of the Gateway Arch in St. Louis, Missouri, with a distant view of the city buildings mirrored in the waterfront
A beautiful twilight view of the Gateway Arch in St. Louis, Missouri, with a distant view of the city buildings mirrored in the waterfront
Septiembre, the first month of the autumn, in St. Louis, is also a moderately hot month, with temperature in the range of an average low of 60.6°F (15.9°C) and an average high of 80.2°F (26.8°C).

Temperature

In St. Louis, the average high-temperature slightly decreases, from a tropical 88°F (31.1°C) in Agosto, to a moderately hot 80.2°F (26.8°C). In Septiembre, in St. Louis, the average low-temperature is 60.6°F (15.9°C).

Humidity

The average relative humidity in St. Louis is 71.6%.

Rainfall

In St. Louis, in Septiembre, it is raining for 7.4 days, with typically 3.13" (79.5mm) of accumulated precipitation. In St. Louis, during the entire year, the rain falls for 112.6 days and collects up to 40.96" (1040.3mm) of precipitation.

Snowfall

Mayo through Octubre are months without snowfall in St. Louis.

Daylight

The average length of the day in St. Louis, Missouri, is 12.4h.

Sunshine

In Septiembre, the average sunshine in St. Louis is 7.9h.

UV index

In Septiembre, the average daily maximum UV index in St. Louis is 7. A UV Index value of 6 to 7 symbolizes a high health vulnerability from the exposure to the Sun's UV radiation for the average person.
Note: The average daily UV index of 7 in Septiembre transform into the following instructions:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. 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 Septiembre in St. Louis?

In St. Louis, in Septiembre, the average high-temperature is 80.2°F (26.8°C), and the average low-temperature is 60.6°F (15.9°C).

What is the average humidity in Septiembre in St. Louis?

In Septiembre, the average relative humidity in St. Louis is 71.6%.

How much does it rain in St. Louis in Septiembre?

In St. Louis, in Septiembre, during 7.4 rainfall days, 3.13" (79.5mm) of precipitation is typically accumulated.

When it does not snow in St. Louis?

Mayo through Octubre are months without snowfall in St. Louis, Missouri.

What is the average length of the day in Septiembre in St. Louis?

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

How long on average sun shines in Septiembre in St. Louis?

In Septiembre, the average sunshine in St. Louis is 7.9h.

What is the UV index reading in Septiembre in St. Louis?

In St. Louis, the average daily maximum UV index in Septiembre is 7. A UV Index of 6 to 7 symbolizes a high health threat from the exposure to the Sun's UV rays.
Average temperature in September - St. Louis, MO
  • Average high temperature in September: 80.2°F

The warmest month (with the highest average high temperature) is July (89.1°F).
The month with the lowest average high temperature is January (39.9°F).

  • Average low temperature in September: 60.6°F

The month with the highest average low temperature is July (71°F).
The coldest month (with the lowest average low temperature) is January (23.7°F).

Average humidity in September - St. Louis, MO
  • Average humidity in September: 71.6%

The month with the highest relative humidity is December (75.8%).
The month with the lowest relative humidity is April (63.5%).

Average rainfall in September - St. Louis, MO
  • Average rainfall in September: 3.1"

The wettest month (with the highest rainfall) is May (4.7").
The driest month (with the lowest rainfall) is February (2.2").

Average rainfall days in September - St. Louis, MO
  • Average rainfall days in September: 7.4 days

The month with the highest number of rainy days is May (11.9 days).
The month with the lowest number of rainy days is September (7.4 days).

Average snowfall in September - St. Louis, MO
  • Average snowfall in September: 0"

The month with the highest snowfall is January (5.6").
Months with the lowest snowfall are May, June, July, August, September and October (0").

Average snowfall days in September - St. Louis, MO
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (4.7 days).
Months with the lowest number of snowfall days are May, June, July, August, September and October (0 days).

Average daylight in September / Average sunshine in September - St. Louis, MO
  • 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: 7.9h

The month with most sunshine is July (Average sunshine: 10h).
The month with least sunshine is December (Average sunshine: 4.2h).

Average UV index in September - St. Louis, MO
  • 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).