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
As August transitions into September, Siam sees a gentle drop in the average high-temperature, transitioning from a warm 82.2°F (27.9°C) to a still moderately hot 76.6°F (24.8°C). September witnesses an average nighttime temperature of 57°F (13.9°C).Humidity
In September, the average relative humidity in Siam is 75%.Rainfall
In Siam, during September, the rain falls for 10.1 days and regularly aggregates up to 1.34" (34mm) of precipitation. Throughout the year, there are 114.9 rainfall days, and 18.39" (467mm) of precipitation is accumulated.Snowfall
May through September are months without snowfall.Daylight
In Siam, the average length of the day in September is 12h and 27min.On the first day of September, sunrise is at 6:47 am and sunset at 7:51 pm. On the last day of the month, sunrise is at 7:15 am and sunset at 7:02 pm CDT.
Sunshine
In September, the average sunshine is 9.3h.UV index
In September, the average daily maximum UV index is 5. A UV Index estimate of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for the average person.Note: The maximum daily UV index of 5 in September interprets into the following recommendations:
Undertake precautions - It is suggested to shield oneself from sunburn. Avoid the Sun's strongest UV rays by seeking shade and limiting exposure during midday. On sunny days, it's ideal to wear sunglasses that filter out UVA and UVB rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
Does it snow in September?
What is the average length of the day in September?
When are sunrise and sunset in September?
How many hours of sunshine does Siam have in September?
How high is the UV index in September?
Average temperature in September
Siam, IA
- Average high temperature in September: 76.6°F
The warmest month (with the highest average high temperature) is July (83.8°F).
The month with the lowest average high temperature is January (31.1°F).
- Average low temperature in September: 57°F
The month with the highest average low temperature is July (66.6°F).
The coldest month (with the lowest average low temperature) is January (17.2°F).
Average pressure in September
Siam, IA
- Average pressure in September: 30"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.87"Hg).
Average wind speed in September
Siam, IA
- Average wind speed in September: 8mph
The windiest month (with the highest average wind speed) is March (10.3mph).
The calmest month (with the lowest average wind speed) is July (6.7mph).
Average humidity in September
Siam, IA
- Average humidity in September: 75%
The month with the highest relative humidity is January (80%).
The month with the lowest relative humidity is October (69%).
Average rainfall in September
Siam, IA
- Average rainfall in September: 1.34"
The wettest month (with the highest rainfall) is June (3.39").
The driest month (with the least rainfall) is February (0.43").
Average rainfall days in September
Siam, IA
- Average rainfall days in September: 10.1 days
The month with the highest number of rainy days is May (16.7 days).
The month with the least rainy days is February (3.4 days).
Average snowfall in September
Siam, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.17").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Siam, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (7.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Siam, IA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in September: 9h and 2min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in September
Siam, IA
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is November (22.5 days).
The month with the least sunshine days is June (12.3 days).
Average UV index in September
Siam, IA
- Average UV index in September: 5
The months with the highest UV index are 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
Siam, IA
- Average cloud cover in September: 28
The month with the most cloud cover is January (Cloud cover 49).
The month with the least cloud cover is July (Cloud cover 27).
Average visibility in September
Siam, IA
- 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).
Siam, Iowa, USA
Weather forecast for your location
2. Allow the app to use your location