Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
With September's onset, the weather reveals a slight temperature decrease, transitioning from a moderately hot 85.5°F (29.7°C) in August to a still warm 79.7°F (26.5°C). Throughout September, Clayton witnesses a nighttime temperature average of 60.1°F (15.6°C).Humidity
In Clayton, the average relative humidity in September is 73%.Rainfall
In Clayton, during September, the rain falls for 12 days and regularly aggregates up to 1.97" (50mm) of precipitation. Throughout the year, there are 144.8 rainfall days, and 30.59" (777mm) of precipitation is accumulated.Snowfall
April through October are months without snowfall.Daylight
In Clayton, the average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:31 am and sunset at 7:30 pm. On the last day of September, sunrise is at 6:56 am and sunset at 6:45 pm CDT.
Sunshine
The average sunshine in September in Clayton is 9.6h.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 unsafe exposure to UV radiation for the average person.Note: The maximum UV index of 5 during September leads to these instructions:
Exercise prudence. Persons with fair skin could be burned in under 30 minutes. During midday, the Sun's radiation is strongest, and it's advisable to reduce direct exposure. Boost your sun resistance with garments that are densely woven yet spacious. Attention! Nearly twice the Sun's UV radiation can be reflected by snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in Clayton in September?
What is the average humidity in September in Clayton?
How many days does it rain in September in Clayton?
When it does not snow in Clayton?
What is the average length of the day in September in Clayton?
What time are sunrise and sunset in September in Clayton?
How long on average sun shines in September in Clayton?
What is the UV index reading in September in Clayton?
Average temperature in September
Clayton, 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 (37.8°F).
- Average low temperature in September: 60.1°F
The month with the highest average low temperature is July (69.1°F).
The coldest month (with the lowest average low temperature) is January (24.3°F).
Average pressure in September
Clayton, 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
Clayton, MO
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is January (9.2mph).
The calmest months (with the lowest average wind speed) are July and August (5.5mph).
Average humidity in September
Clayton, 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 (70%).
Average rainfall in September
Clayton, MO
- Average rainfall in September: 1.97"
The wettest month (with the highest rainfall) is May (3.58").
The driest month (with the least rainfall) is February (1.69").
Average rainfall days in September
Clayton, MO
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is May (16.9 days).
The month with the least rainy days is January (6.5 days).
Average snowfall in September
Clayton, 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
Clayton, MO
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is February (5.2 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Clayton, MO
- Average daylight in September: 12h and 2min
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 4min
The months with the most sunshine are June and July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in September
Clayton, MO
- Average sunshine days in September: 15.2 days
The month with the most sunshine days is January (21 days).
The month with the least sunshine days is June (11.2 days).
Average UV index in September
Clayton, 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
Clayton, MO
- Average cloud cover in September: 28
The month with the most cloud cover is January (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 27).
Average visibility in September
Clayton, 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).
Clayton, Missouri, USA
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