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
Altamont's shift into September is marked by a subtle change to a still moderately hot 77.5°F (25.3°C) from August's 82.2°F (27.9°C) in temperature. Altamont observes an average low-temperature of 59.4°F (15.2°C) during September nights.Humidity
In September, the average relative humidity is 75%.Rainfall
In Altamont, Illinois, during September, the rain falls for 10.8 days and regularly aggregates up to 1.54" (39mm) of precipitation. In Altamont, during the entire year, the rain falls for 141.3 days and collects up to 26.77" (680mm) of precipitation.Snowfall
April through October are months without snowfall.Daylight
In September, the average length of the day is 12h and 26min.On the first day of September, sunrise is at 6:24 am and sunset at 7:25 pm. On the last day of the month, sunrise is at 6:50 am and sunset at 6:38 pm CDT.
Sunshine
In Altamont, the average sunshine in September is 9.2h.UV index
In September, the average daily maximum UV index is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for the average person.Note: The maximum UV index of 5 during September leads to these instructions:
Exercise caution. Those with pale skin may experience burns in less than half an hour. The midday Sun can be harmful due to its potent UV radiation; seek shade and reduce exposure. During bright days, sunglasses that offer UVA and UVB defense are recommended.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Altamont in September?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
How many hours of daylight does Altamont have in September?
What time are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index reading in September?
Average temperature in September
Altamont, IL
- Average high temperature in September: 77.5°F
The warmest month (with the highest average high temperature) is July (83.7°F).
The month with the lowest average high temperature is January (35.6°F).
- Average low temperature in September: 59.4°F
The month with the highest average low temperature is July (67.1°F).
The coldest month (with the lowest average low temperature) is January (23.4°F).
Average pressure in September
Altamont, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Altamont, IL
- Average wind speed in September: 6.7mph
The windiest months (with the highest average wind speed) are January and February (10.3mph).
The calmest months (with the lowest average wind speed) are July and August (6mph).
Average humidity in September
Altamont, IL
- Average humidity in September: 75%
The months with the highest relative humidity are July and August (81%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Altamont, IL
- Average rainfall in September: 1.54"
The wettest month (with the highest rainfall) is April (3.35").
The driest month (with the least rainfall) is February (1.38").
Average rainfall days in September
Altamont, IL
- Average rainfall days in September: 10.8 days
The month with the highest number of rainy days is May (17.5 days).
The month with the least rainy days is January (7.3 days).
Average snowfall in September
Altamont, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.01").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Altamont, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (5.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Altamont, IL
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is June (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 18min).
Average sunshine days in September
Altamont, IL
- Average sunshine days in September: 17.1 days
The month with the most sunshine days is December (19.5 days).
The month with the least sunshine days is May (10.8 days).
Average UV index in September
Altamont, IL
- 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
Altamont, IL
- Average cloud cover in September: 29
The month with the most cloud cover is January (Cloud cover 53).
The months with the least cloud cover are June and September (Cloud cover 29).
Average visibility in September
Altamont, IL
- 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).
Altamont, Illinois, USA
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