September weather forecastNorthbrook, IL
September
Weather in September
The first month of the autumn, September, is also an agreeable month in Northbrook, Illinois, with an average temperature fluctuating between 60.3°F (15.7°C) and 71.6°F (22°C).Temperature
September brings a minor shift in the average high-temperature, adjusting from a warm 78.1°F (25.6°C) in August to an agreeable 71.6°F (22°C). In Northbrook, September nights cool down to an average of 60.3°F (15.7°C).Humidity
The average relative humidity in September is 74%.Rainfall
In Northbrook, during September, the rain falls for 14.8 days and regularly aggregates up to 2.87" (73mm) of precipitation. Throughout the year, there are 164.7 rainfall days, and 35.28" (896mm) of precipitation is accumulated.Snowfall
In Northbrook, snow does not fall in June through September.Daylight
The average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:17 am and sunset at 7:24 pm. On the last day of September, sunrise is at 6:48 am and sunset at 6:34 pm CDT.
Sunshine
In September, the average sunshine is 9h.UV index
In Northbrook, 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 ordinary individuals.Note: The maximum UV index of 4 during September translates into these guidelines:
Make use of precautions - It is urged to ward off sun damage. To avoid the Sun's strongest rays, limit exposure around the mid-day period. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Northbrook, IL
- Average high temperature in September: 71.6°F
The warmest month (with the highest average high temperature) is July (79.2°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in September: 60.3°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 (18.9°F).
Average pressure in September
Northbrook, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Northbrook, IL
- Average wind speed in September: 8.6mph
The windiest month (with the highest average wind speed) is January (11.5mph).
The calmest month (with the lowest average wind speed) is August (7.1mph).
Average humidity in September
Northbrook, IL
- Average humidity in September: 74%
The month with the highest relative humidity is January (82%).
The month with the lowest relative humidity is October (73%).
Average rainfall in September
Northbrook, IL
- Average rainfall in September: 2.87"
The wettest months (with the highest rainfall) are May and June (4.57").
The driest month (with the least rainfall) is December (1.65").
Average rainfall days in September
Northbrook, IL
- Average rainfall days in September: 14.8 days
The month with the highest number of rainy days is May (19.1 days).
The month with the least rainy days is February (6.1 days).
Average snowfall in September
Northbrook, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.84").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Northbrook, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Northbrook, IL
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 9h and 0min
The months with the most sunshine are July and August (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in September
Northbrook, IL
- Average sunshine days in September: 11.7 days
The month with the most sunshine days is November (15.5 days).
The month with the least sunshine days is June (9.2 days).
Average UV index in September
Northbrook, IL
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in September
Northbrook, IL
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 61).
The months with the least cloud cover are July and August (Cloud cover 28).
Average visibility in September
Northbrook, 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).
