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
The average high-temperature during September registers at an agreeable 72.7°F (22.6°C), closely corresponding to the preceding month. The temperature dips to an average of 54°F (12.2°C) during September nights.Humidity
In Duncan, the average relative humidity in September is 76%.Rainfall
In Duncan, in September, it is raining for 11.5 days, with typically 2.48" (63mm) of accumulated precipitation. In Duncan, during the entire year, the rain falls for 127.1 days and collects up to 24.8" (630mm) of precipitation.Snowfall
June through September are months without snowfall.Daylight
In September, the average length of the day is 12h and 29min.On the first day of September in Duncan, sunrise is at 6:40 am and sunset at 7:49 pm. On the last day of the month, sunrise is at 7:11 am and sunset at 6:57 pm CDT.
Sunshine
In Duncan, the average sunshine in September is 9h.UV index
The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for the average person.Note: The maximum UV index of 4 during September leads to these instructions:
Exercise prevention - Warding off sunburn is urged. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
Does it snow in September?
How many hours of daylight does Duncan have in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Duncan have in September?
What is the UV index reading in September?
Average temperature in September
Duncan, IA
- Average high temperature in September: 72.7°F
The warmest month (with the highest average high temperature) is July (79.7°F).
The month with the lowest average high temperature is January (22.8°F).
- Average low temperature in September: 54°F
The month with the highest average low temperature is July (63°F).
The coldest month (with the lowest average low temperature) is January (10.4°F).
Average pressure in September
Duncan, IA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
Duncan, IA
- Average wind speed in September: 8.6mph
The windiest month (with the highest average wind speed) is April (11mph).
The calmest month (with the lowest average wind speed) is July (7.4mph).
Average humidity in September
Duncan, IA
- Average humidity in September: 76%
The month with the highest relative humidity is January (89%).
The month with the lowest relative humidity is October (69%).
Average rainfall in September
Duncan, IA
- Average rainfall in September: 2.48"
The wettest month (with the highest rainfall) is June (3.82").
The driest month (with the least rainfall) is January (0.94").
Average rainfall days in September
Duncan, IA
- Average rainfall days in September: 11.5 days
The month with the highest number of rainy days is June (17.8 days).
The month with the least rainy days is February (2.8 days).
Average snowfall in September
Duncan, IA
- Average snowfall in September: 0"
The month with the highest snowfall is February (5.71").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Duncan, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Duncan, IA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 9h and 0min
The month with the most sunshine is July (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Duncan, IA
- Average sunshine days in September: 16.4 days
The month with the most sunshine days is November (18.3 days).
The month with the least sunshine days is June (10.4 days).
Average UV index in September
Duncan, IA
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Duncan, IA
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 62).
The months with the least cloud cover are August and September (Cloud cover 32).
Average visibility in September
Duncan, IA
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, August, September, October, November and December (6mi).
The months with the lowest visibility are January and July (5mi).
Duncan, Iowa, USA
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