September weather forecastSaint Clair, MO
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Saint Clair, Missouri, with temperature in the range of an average high of 80.2°F (26.8°C) and an average low of 59.2°F (15.1°C).Temperature
September's arrival coincides with a soft drop in the average high-temperature, subtly decreasing from August's tropical 87.3°F (30.7°C) to a moderately hot 80.2°F (26.8°C). Throughout September, Saint Clair experiences a low-temperature average of 59.2°F (15.1°C).Humidity
The average relative humidity in September is 74%.Rainfall
In Saint Clair, during September, the rain falls for 9.8 days and regularly aggregates up to 1.46" (37mm) of precipitation. Throughout the year, there are 126.7 rainfall days, and 20.63" (524mm) of precipitation is accumulated.Snowfall
April through October are months without snowfall.Daylight
In September, the average length of the day is 12h and 25min.On the first day of the month, sunrise is at 6:34 am and sunset at 7:33 pm. On the last day of September, in Saint Clair, sunrise is at 6:59 am and sunset at 6:47 pm CDT.
Sunshine
In September, the average sunshine is 9.4h.UV index
In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.Note: The UV index of 5 during September leads to these advisories:
Prioritize safety - Suggestions to prevent sun damage are offered. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Employ a hat with a wide brim for robust protection, cutting UV exposure by half. Mind you! Snow reflection can increase the intensity of the Sun's UV radiation nearly twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Saint Clair, MO
- Average high temperature in September: 80.2°F
The warmest month (with the highest average high temperature) is July (88.9°F).
The month with the lowest average high temperature is January (39°F).
- Average low temperature in September: 59.2°F
The month with the highest average low temperature is July (68°F).
The coldest month (with the lowest average low temperature) is January (24.3°F).
Average pressure in September
Saint Clair, 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
Saint Clair, MO
- Average wind speed in September: 5.7mph
The windiest month (with the highest average wind speed) is January (8.5mph).
The calmest months (with the lowest average wind speed) are July and August (5.3mph).
Average humidity in September
Saint Clair, MO
- Average humidity in September: 74%
The month with the highest relative humidity is May (78%).
The month with the lowest relative humidity is October (72%).
Average rainfall in September
Saint Clair, MO
- Average rainfall in September: 1.46"
The wettest months (with the highest rainfall) are April and May (2.48").
The driest months (with the least rainfall) are January and February (0.98").
Average rainfall days in September
Saint Clair, MO
- Average rainfall days in September: 9.8 days
The month with the highest number of rainy days is May (15.4 days).
The month with the least rainy days is January (5.9 days).
Average snowfall in September
Saint Clair, MO
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.57").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Saint Clair, MO
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is January (6.2 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Saint Clair, 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 months with the most sunshine are June and July (Average sunshine: 10h and 24min).
The months with the least sunshine are January and February (Average sunshine: 4h and 42min).
Average sunshine days in September
Saint Clair, MO
- Average sunshine days in September: 18.1 days
The month with the most sunshine days is January (20.6 days).
The month with the least sunshine days is May (13.7 days).
Average UV index in September
Saint Clair, 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, November and December (UV index 2).
Average cloud cover in September
Saint Clair, MO
- Average cloud cover in September: 31
The months with the most cloud cover are January and February (Cloud cover 49).
The months with the least cloud cover are June and July (Cloud cover 29).
Average visibility in September
Saint Clair, MO
- Average visibility in September: 5mi
The months with the highest visibility are January, February, March, April, June, July, October, November and December (6mi).
The months with the lowest visibility are May, August and September (5mi).
