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
The transition into September involves a small decrease in the average high-temperature, dipping slightly from a moderately hot 85.5°F (29.7°C) in August to a still warm 79.7°F (26.5°C). September sees the temperature falling to a mean low of 60.1°F (15.6°C).Humidity
In Saint Johns, Illinois, the average relative humidity in September is 74%.Rainfall
In Saint Johns, in September, during 11.6 rainfall days, 1.73" (44mm) of precipitation is typically accumulated. Throughout the year, in Saint Johns, there are 147.6 rainfall days, and 29.17" (741mm) of precipitation is accumulated.Snowfall
May through October are months without snowfall in Saint Johns, Illinois.Daylight
In September, the average length of the day in Saint Johns is 12h and 25min.On the first day of the month, sunrise is at 6:27 am and sunset at 7:26 pm. On the last day of September, in Saint Johns, sunrise is at 6:52 am and sunset at 6:40 pm CDT.
Sunshine
In Saint Johns, the average sunshine in September is 9.2h.UV index
In September, the average daily maximum UV index in Saint Johns is 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from unprotected exposure to Sun's UV rays for the average person.Note: A typical high UV index of 5 in September suggests the following recommendations:
Exercise prevention - Precautions against solar damage are endorsed. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Frequently asked questions
What is the average September temperature in Saint Johns?
What is the average humidity in September in Saint Johns?
How many days does it rain in September in Saint Johns?
When it does not snow in Saint Johns?
How many hours of daylight does Saint Johns have in September?
When are sunrise and sunset in September in Saint Johns?
How long on average sun shines in September in Saint Johns?
What is the UV index intensity in September in Saint Johns?
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 2min
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 1min
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).
Saint Johns, Illinois, USA
Weather forecast for your location
2. Allow the app to use your location
