September weather forecastSaint Louis, MI
September
Weather in September
September, the first month of the autumn in Saint Louis, is also an agreeable month, with an average temperature varying between 52.3°F (11.3°C) and 71.1°F (21.7°C).Temperature
The beginning of September subtly marks a decrease in the average high-temperature, transitioning from a moderately hot 77.5°F (25.3°C) in August to a pleasant 71.1°F (21.7°C). In the month of September, Saint Louis's average low-temperature falls to a cool 52.3°F (11.3°C).Humidity
In September, the average relative humidity is 79%.Rainfall
In Saint Louis, in September, it is raining for 11.6 days, with typically 1.46" (37mm) of accumulated precipitation. Throughout the year, in Saint Louis, there are 141.3 rainfall days, and 22.48" (571mm) of precipitation is accumulated.Snowfall
In Saint Louis, snow does not fall in May through September.Daylight
In Saint Louis, the average length of the day in September is 12h and 29min.On the first day of the month, sunrise is at 7:03 am and sunset at 8:13 pm. On the last day of September, sunrise is at 7:35 am and sunset at 7:20 pm EDT.
Sunshine
The average sunshine in September is 8.1h.UV index
In September, the average daily maximum UV index is 3. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for ordinary individuals.Note: In September, the UV index of 3 transforms into the following advice:
Prioritize safety - Suggestions to prevent sun damage are offered. Limiting sun exposure during midday hours helps in reducing the harmful effects of UV radiation. A wide-brimmed hat is a shield, deflecting up to 50% of harmful UV radiation from eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Saint Louis, MI
- Average high temperature in September: 71.1°F
The warmest month (with the highest average high temperature) is July (79.3°F).
The month with the lowest average high temperature is January (26.8°F).
- Average low temperature in September: 52.3°F
The month with the highest average low temperature is July (60.4°F).
The coldest month (with the lowest average low temperature) is January (16.2°F).
Average pressure in September
Saint Louis, MI
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is March (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Saint Louis, MI
- Average wind speed in September: 7.3mph
The windiest month (with the highest average wind speed) is April (9.9mph).
The calmest month (with the lowest average wind speed) is July (6.6mph).
Average humidity in September
Saint Louis, MI
- Average humidity in September: 79%
The month with the highest relative humidity is January (88%).
The month with the lowest relative humidity is April (75%).
Average rainfall in September
Saint Louis, MI
- Average rainfall in September: 1.46"
The wettest month (with the highest rainfall) is May (3.03").
The driest month (with the least rainfall) is February (1.26").
Average rainfall days in September
Saint Louis, MI
- Average rainfall days in September: 11.6 days
The month with the highest number of rainy days is May (15.9 days).
The month with the least rainy days is February (5.3 days).
Average snowfall in September
Saint Louis, MI
- Average snowfall in September: 0"
The month with the highest snowfall is January (5.91").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Saint Louis, MI
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (18 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Saint Louis, MI
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).
- Average sunshine in September: 8h and 6min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 2h and 42min).
Average sunshine days in September
Saint Louis, MI
- Average sunshine days in September: 15.8 days
The month with the most sunshine days is September (15.8 days).
The month with the least sunshine days is January (10.3 days).
Average UV index in September
Saint Louis, MI
- Average UV index in September: 3
The months with the highest UV index are May, June, July and August (UV index 5).
The months with the lowest UV index are January, November and December (UV index 1).
Average cloud cover in September
Saint Louis, MI
- Average cloud cover in September: 35
The month with the most cloud cover is January (Cloud cover 71).
The month with the least cloud cover is July (Cloud cover 30).
Average visibility in September
Saint Louis, MI
- Average visibility in September: 5mi
The months with the highest visibility are March, April, May, June, July, August, October and November (6mi).
The months with the lowest visibility are January, February, September and December (5mi).
