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
September's arrival brings an average high-temperature of a still moderately hot 75.7°F (24.3°C), slightly deviating from August's 79.7°F (26.5°C). In Forrest, September nights cool down to an average of 57.2°F (14°C).Humidity
The average relative humidity in September is 76%.Rainfall
In Forrest, during September, the rain falls for 10.5 days and regularly aggregates up to 1.18" (30mm) of precipitation. In Forrest, during the entire year, the rain falls for 130.5 days and collects up to 17.44" (443mm) of precipitation.Snowfall
May through September are months without snowfall.Daylight
The average length of the day in September in Forrest is 12h and 27min.On the first day of September, sunrise is at 6:21 am and sunset at 7:25 pm. On the last day of the month, sunrise is at 6:49 am and sunset at 6:36 pm CDT.
Sunshine
The average sunshine in September is 8.9h.UV index
In Forrest, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for the ordinary person.Note: In September, a daily maximum UV index of 4 leads to the following instructions:
Act with care - Obligation to protect against skin and eye damage is highlighted. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. To cut down UV radiation exposure by about half, sport a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
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?
What time are sunrise and sunset in September?
How long on average sun shines in September?
How high is the UV index in September?
Average temperature in September
Forrest, IL
- Average high temperature in September: 75.7°F
The warmest month (with the highest average high temperature) is July (80.8°F).
The month with the lowest average high temperature is January (30.6°F).
- Average low temperature in September: 57.2°F
The month with the highest average low temperature is July (64.6°F).
The coldest month (with the lowest average low temperature) is January (18.5°F).
Average pressure in September
Forrest, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Forrest, IL
- Average wind speed in September: 7.6mph
The windiest month (with the highest average wind speed) is January (10.8mph).
The calmest month (with the lowest average wind speed) is August (6.4mph).
Average humidity in September
Forrest, IL
- Average humidity in September: 76%
The month with the highest relative humidity is July (86%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Forrest, IL
- Average rainfall in September: 1.18"
The wettest month (with the highest rainfall) is May (2.56").
The driest month (with the least rainfall) is January (0.79").
Average rainfall days in September
Forrest, IL
- Average rainfall days in September: 10.5 days
The month with the highest number of rainy days is May (17 days).
The months with the least rainy days are January and February (5 days).
Average snowfall in September
Forrest, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.09").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Forrest, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (10.6 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Forrest, IL
- Average daylight in September: 12h and 3min
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: 8h and 5min
The month with the most sunshine is June (Average sunshine: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).
Average sunshine days in September
Forrest, IL
- Average sunshine days in September: 17.2 days
The month with the most sunshine days is November (19.5 days).
The month with the least sunshine days is July (11.4 days).
Average UV index in September
Forrest, IL
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in September
Forrest, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 59).
The month with the least cloud cover is September (Cloud cover 32).
Average visibility in September
Forrest, IL
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
Forrest, Illinois, USA
Weather forecast for your location
2. Allow the app to use your location