September weather forecastAffton, MO
September
Weather in September
In September, Affton, Missouri sees a dip in temperatures, marking the change from summer to fall. The weather shifts drive many to engage in activities that align with this transitional season. Whilst the summer heat starts to wind down, the cooling evenings cultivate a sense of tranquility and peace. September is known for being ripe with harvests, filled bountifully with the fruits of summer’s labor. It sets the stage for the breathtaking display of autumn colors that Affton is known for.Temperature
September brings a minor shift in the average high-temperature in Affton, adjusting from a moderately hot 85.6°F (29.8°C) in August to a still warm 79.7°F (26.5°C). Throughout September, the average low-temperature in Affton dips to a mild 59.9°F (15.5°C).Humidity
In Affton, the average relative humidity in September is 73%.Rainfall
In Affton, Missouri, in September, it is raining for 12.6 days, with typically 2.13" (54mm) of accumulated precipitation. Throughout the year, there are 146.1 rainfall days, and 32.36" (822mm) of precipitation is accumulated.Snowfall
In Affton, snow does not fall in April through October.Daylight
The average length of the day in September is 12h and 25min.On the first day of September, sunrise is at 6:31 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:56 am and sunset at 6:45 pm CDT.
Sunshine
In September, the average sunshine is 9.4h.UV index
The average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV radiation for average individuals.Note: In September, the maximum UV index of 5 suggests these recommendations:
Act with care - The suggestion to avoid sunburn is emphasized. The midday Sun can be harmful due to its potent UV radiation; seek shade and reduce exposure. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Affton, MO
- Average high temperature in September: 79.7°F
The warmest month (with the highest average high temperature) is July (86.9°F).
The month with the lowest average high temperature is January (37.9°F).
- Average low temperature in September: 59.9°F
The month with the highest average low temperature is July (69.3°F).
The coldest month (with the lowest average low temperature) is January (25°F).
Average pressure in September
Affton, MO
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Affton, MO
- Average wind speed in September: 5.9mph
The windiest month (with the highest average wind speed) is January (9.1mph).
The calmest months (with the lowest average wind speed) are July and August (5.5mph).
Average humidity in September
Affton, MO
- Average humidity in September: 73%
The month with the highest relative humidity is May (78%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Affton, MO
- Average rainfall in September: 2.13"
The wettest month (with the highest rainfall) is May (3.94").
The driest months (with the least rainfall) are February and November (1.77").
Average rainfall days in September
Affton, MO
- Average rainfall days in September: 12.6 days
The month with the highest number of rainy days is July (16.9 days).
The months with the least rainy days are January and February (6.8 days).
Average snowfall in September
Affton, MO
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.6").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Affton, MO
- Average snowfall days in September: 0 days
The months with the highest number of snowfall days are January and February (4.8 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
Affton, MO
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 9h and 24min
The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).
Average sunshine days in September
Affton, MO
- Average sunshine days in September: 15.5 days
The month with the most sunshine days is January (20.9 days).
The month with the least sunshine days is June (11.6 days).
Average UV index in September
Affton, MO
- Average UV index in September: 5
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 and December (UV index 2).
Average cloud cover in September
Affton, MO
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 51).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility in September
Affton, MO
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
