September weather forecast
Saint Louis, VA

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Weather in September

September, the first month of the autumn in Saint Louis, is still a warm month, with an average temperature fluctuating between 58.3°F (14.6°C) and 77.4°F (25.2°C).

Temperature

September is marked by a subtle drop in average high-temperatures, transitioning from 84.6°F (29.2°C) in August to a still moderately hot 77.4°F (25.2°C). Saint Louis registers a consistent average low-temperature of 58.3°F (14.6°C) during September.

Humidity

In September, the average relative humidity is 77%.

Rainfall

September is the month with the least rainfall. Rain falls for 13.7 days and accumulates 1.93" (49mm) of precipitation.

Snowfall

May through September are months without snowfall.

Daylight

In September, the average length of the day is 12h and 26min.
On the first day of September, sunrise is at 6:40 am and sunset at 7:41 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 6:54 pm EDT.

Sunshine

In September, the average sunshine is 8.9h.

UV index

In September, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for ordinary individuals.
Note: The UV index of 4 in September translates into these instructions:
Be vigilant - Suggestions to stave off sun damage are provided. For health reasons, it's advisable to reduce direct sun exposure during peak hours around midday. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure.
Updated: Jul 22, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for Saint Louis in September?

During September, Saint Louis experiences an average high-temperature of 77.4°F (25.2°C) and a low-temperature of 58.3°F (14.6°C). In August, the average heat index (a.k.a. 'apparent temperature', 'feels like'), which represents the influence of relative humidity on air temperature, is computed to be 93.2°F (34°C).

What is the average humidity in September?

In September, the average relative humidity is 77%.

What is the driest month?

September is the month with the least rainfall. Rain falls for 13.7 days and accumulates 1.93" (49mm) of precipitation.

How much does it rain in September?

In Saint Louis, during September, the rain falls for 13.7 days and regularly aggregates up to 1.93" (49mm) of precipitation.

When it does not snow?

May through September are months without snowfall.

Does it snow in September?

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

How many hours of daylight does Saint Louis have in September?

In Saint Louis, the average day length in September is 12h and 26min.

What time are sunrise and sunset in September in Saint Louis?

In September, on the first day of the month, sunrise is at 6:40 am and sunset at 7:41 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 6:54 pm EDT.

How long on average sun shines in September?

In Saint Louis, the average sunshine duration in September is 8.9h.

What is the UV index reading in September?

In Saint Louis, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate health threat from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Saint Louis, VA

Average temperature in September - Saint Louis, VA
  • Average high temperature in September: 77.4°F

The warmest month (with the highest average high temperature) is July (86.5°F).
The month with the lowest average high temperature is January (38.7°F).

  • Average low temperature in September: 58.3°F

The month with the highest average low temperature is July (65.5°F).
The coldest month (with the lowest average low temperature) is January (24.8°F).

Average pressure in September
Saint Louis, VA

Average pressure in September - Saint Louis, VA
  • Average pressure in September: 30.06"Hg

The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).

Average wind speed in September
Saint Louis, VA

Average wind speed in September - Saint Louis, VA
  • Average wind speed in September: 5mph

The windiest month (with the highest average wind speed) is March (7.3mph).
The calmest month (with the lowest average wind speed) is August (4.4mph).

Average humidity in September
Saint Louis, VA

Average humidity in September - Saint Louis, VA
  • Average humidity in September: 77%

The months with the highest relative humidity are October and December (78%).
The month with the lowest relative humidity is July (73%).

Average rainfall in September
Saint Louis, VA

Average rainfall in September - Saint Louis, VA
  • Average rainfall in September: 1.93"

The wettest months (with the highest rainfall) are May and August (3.35").
The driest month (with the least rainfall) is September (1.93").

Average rainfall days in September
Saint Louis, VA

Average rainfall days in September - Saint Louis, VA
  • Average rainfall days in September: 13.7 days

The month with the highest number of rainy days is May (17.3 days).
The month with the least rainy days is January (10.1 days).

Average snowfall in September
Saint Louis, VA

Average snowfall in September - Saint Louis, VA
  • Average snowfall in September: 0"

The month with the highest snowfall is January (4.17").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days in September
Saint Louis, VA

Average snowfall days in September - Saint Louis, VA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (6.8 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

Average daylight in September /
Average sunshine in September
Saint Louis, VA

Average daylight in September / Average sunshine in September - Saint Louis, VA
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in September: 8h and 5min

The month with the most sunshine is July (Average sunshine: 10h and 48min).
The months with the least sunshine are January and December (Average sunshine: 5h and 6min).

Average sunshine days in September
Saint Louis, VA

Average sunshine days in September - Saint Louis, VA
  • Average sunshine days in September: 14.7 days

The month with the most sunshine days is November (19.3 days).
The month with the least sunshine days is May (11.1 days).

Average UV index in September
Saint Louis, VA

Average UV index in September - Saint Louis, VA
  • Average UV index in September: 4

The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in September
Saint Louis, VA

Average cloud cover in September - Saint Louis, VA
  • Average cloud cover in September: 36

The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 30).

Average visibility in September
Saint Louis, VA

Average visibility in September - Saint Louis, VA
  • Average visibility in September: 5mi

The months with the highest visibility are February, March, April, June, July, August and November (6mi).
The months with the lowest visibility are January, May, September, October and December (5mi).

Saint Louis, Virginia, USA

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