September weather forecastSaint Johns, IL
September
Weather in September
The first month of the autumn, September, is still a warm month in Saint Johns, Illinois, with an average temperature ranging between min 60.1°F (15.6°C) and max 79.7°F (26.5°C).Temperature
With the beginning of September, the average high-temperature shows a small decrease, transitioning from a warm 85.5°F (29.7°C) in August to a still moderately hot 79.7°F (26.5°C). An average low-temperature of 60.1°F (15.6°C) marks the month of September.Humidity
The average relative humidity in September in Saint Johns, Illinois, is 74%.Rainfall
In September, the rain falls for 11.6 days. Throughout September, 1.73" (44mm) of precipitation is accumulated. In Saint Johns, during the entire year, the rain falls for 147.6 days and collects up to 29.17" (741mm) of precipitation.Snowfall
In Saint Johns, snow does not fall in May through October.Daylight
The average length of the day in September is 12h and 25min.On the first day of September, sunrise is at 6:27 am and sunset at 7:26 pm. On the last day of the month, sunrise is at 6:52 am and sunset at 6:40 pm CDT.
Sunshine
The average sunshine in September is 9.2h.UV index
The average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for average individuals.Note: The maximum daily UV index of 5 during September translates into the following directions:
Take heed. Individuals of lighter complexion can be burned in less than half an hour. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Saint Johns, IL
- Average high temperature in September: 79.7°F
The warmest month (with the highest average high temperature) is July (87.3°F).
The month with the lowest average high temperature is January (38.8°F).
- Average low temperature in September: 60.1°F
The month with the highest average low temperature is July (68.7°F).
The coldest month (with the lowest average low temperature) is January (25.7°F).
Average pressure in September
Saint Johns, 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
Saint Johns, IL
- Average wind speed in September: 6.3mph
The windiest months (with the highest average wind speed) are January and February (9.6mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).
Average humidity in September
Saint Johns, IL
- Average humidity in September: 74%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Saint Johns, IL
- Average rainfall in September: 1.73"
The wettest month (with the highest rainfall) is April (3.58").
The driest month (with the least rainfall) is January (1.5").
Average rainfall days in September
Saint Johns, IL
- Average rainfall days in September: 11.6 days
The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is December (8.2 days).
Average snowfall in September
Saint Johns, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.5").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Saint Johns, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (5.4 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
Saint Johns, IL
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 9h and 12min
The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in September
Saint Johns, IL
- Average sunshine days in September: 16.7 days
The months with the most sunshine days are October and November (19.5 days).
The month with the least sunshine days is May (11.4 days).
Average UV index in September
Saint Johns, 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
Saint Johns, IL
- Average cloud cover in September: 29
The months with the most cloud cover are January and February (Cloud cover 50).
The month with the least cloud cover is June (Cloud cover 28).
Average visibility in September
Saint Johns, 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).
