September weather forecastBoulder Hill, IL
September
Weather in September
The first month of the autumn, September, is still a warm month in Boulder Hill, Illinois, with temperature in the range of an average low of 56.3°F (13.5°C) and an average high of 74.1°F (23.4°C).Temperature
The average high-temperature during September is a still warm 74.1°F (23.4°C), almost matching the conditions of the preceding month. In September, Boulder Hill experiences an average nighttime temperature of 56.3°F (13.5°C).Humidity
The average relative humidity in September is 78%.Rainfall
In September, the rain falls for 12 days. Throughout September, 1.3" (33mm) of precipitation is accumulated. In Boulder Hill, during the entire year, the rain falls for 133.1 days and collects up to 16.93" (430mm) of precipitation.Snowfall
In Boulder Hill, snow does not fall in May through September.Daylight
In September, the average length of the day in Boulder Hill is 12h and 28min.On the first day of the month, sunrise is at 6:20 am and sunset at 7:26 pm. On the last day of September, sunrise is at 6:49 am and sunset at 6:36 pm CDT.
Sunshine
In September, the average sunshine in Boulder Hill, Illinois, is 8.7h.UV index
In September, the average daily maximum UV index in Boulder Hill, Illinois, is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for ordinary individuals.Note: In September, a regular UV index of 4 translates into these guidelines:
Undertake precautions - Guarding against sun damage is counselled. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Boulder Hill, IL
- Average high temperature in September: 74.1°F
The warmest month (with the highest average high temperature) is July (81.1°F).
The month with the lowest average high temperature is January (28.4°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is July (64.2°F).
The coldest month (with the lowest average low temperature) is January (16.7°F).
Average pressure in September
Boulder Hill, 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
Boulder Hill, IL
- Average wind speed in September: 7mph
The windiest month (with the highest average wind speed) is April (9.7mph).
The calmest month (with the lowest average wind speed) is August (6mph).
Average humidity in September
Boulder Hill, IL
- Average humidity in September: 78%
The months with the highest relative humidity are January, February, July and August (83%).
The month with the lowest relative humidity is October (74%).
Average rainfall in September
Boulder Hill, IL
- Average rainfall in September: 1.3"
The wettest month (with the highest rainfall) is June (2.24").
The driest months (with the least rainfall) are November and December (0.75").
Average rainfall days in September
Boulder Hill, IL
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is July (16.6 days).
The month with the least rainy days is February (4.3 days).
Average snowfall in September
Boulder Hill, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.73").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Boulder Hill, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (10.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Boulder Hill, 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: 8h and 42min
The month with the most sunshine is July (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).
Average sunshine days in September
Boulder Hill, IL
- Average sunshine days in September: 14.5 days
The month with the most sunshine days is November (19.5 days).
The month with the least sunshine days is July (10.2 days).
Average UV index in September
Boulder Hill, IL
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Boulder Hill, IL
- Average cloud cover in September: 32
The month with the most cloud cover is January (Cloud cover 60).
The month with the least cloud cover is September (Cloud cover 32).
Average visibility in September
Boulder Hill, 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).
