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 observes an average high-temperature of a still moderately hot 76.1°F (24.5°C), marking an insignificant difference from August's 81.1°F (27.3°C). An average nighttime temperature of 58.3°F (14.6°C) is observed in McLean during September.Humidity
In September, the average relative humidity is 76%.Rainfall
In September, in McLean, the rain falls for 11.4 days. Throughout September, 1.46" (37mm) of precipitation is accumulated. In McLean, during the entire year, the rain falls for 135 days and collects up to 17.72" (450mm) of precipitation.Snowfall
In McLean, snow does not fall in May through October.Daylight
In September, the average length of the day in McLean is 12h and 27min.On the first day of September in McLean, sunrise is at 6:24 am and sunset at 7:28 pm. On the last day of the month, sunrise is at 6:52 am and sunset at 6:40 pm CDT.
Sunshine
In September, the average sunshine in McLean is 9.2h.UV index
The average daily maximum UV index in September in McLean, Illinois, is 5. A UV Index of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for the average person.Note: The average daily UV index of 5 in September transforms into the following instructions:
Preventative actions are necessary - The mandate to avoid skin and eye damage is in place. Direct Sun exposure should be minimized especially during midday when radiation is most intense. 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 usual temperature for McLean in September?
What is the average humidity in September in McLean?
How much does it rain in McLean in September?
When it does not snow in McLean?
What is the average length of the day in September in McLean?
What time are sunrise and sunset in September in McLean?
How many hours of sunshine does McLean have in September?
What is the UV index intensity in September in McLean?
Average temperature in September
McLean, IL
- Average high temperature in September: 76.1°F
The warmest month (with the highest average high temperature) is July (81.5°F).
The month with the lowest average high temperature is January (31.6°F).
- Average low temperature in September: 58.3°F
The month with the highest average low temperature is July (65.1°F).
The coldest month (with the lowest average low temperature) is January (19.8°F).
Average pressure in September
McLean, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
McLean, IL
- Average wind speed in September: 7.5mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (6.3mph).
Average humidity in September
McLean, IL
- Average humidity in September: 76%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is October (70%).
Average rainfall in September
McLean, IL
- Average rainfall in September: 1.46"
The wettest month (with the highest rainfall) is May (2.2").
The driest month (with the least rainfall) is December (0.87").
Average rainfall days in September
McLean, IL
- Average rainfall days in September: 11.4 days
The month with the highest number of rainy days is May (16.5 days).
The month with the least rainy days is February (5.9 days).
Average snowfall in September
McLean, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.2").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
McLean, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.5 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
McLean, IL
- 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 24min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is June (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in September
McLean, IL
- Average sunshine days in September: 17.1 days
The months with the most sunshine days are November and December (20 days).
The month with the least sunshine days is May (11.6 days).
Average UV index in September
McLean, 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
McLean, IL
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 57).
The month with the least cloud cover is September (Cloud cover 30).
Average visibility in September
McLean, 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).
McLean, Illinois, USA
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