September weather forecastMarion, IL
September
Weather in September
September in Marion, Illinois, marks the arrival of the fall season with a significant drop in temperature. The averages take a plunge from the highs of summer to 80.8°F (27.1°C) and the lows to 60.4°F (15.8°C). The shift to fall is evident with cooler temperatures and reduced daylight hours. Despite the decrease in rainfall, September manages to keep lower than average humidity levels. Moving into October, a further fall in temperature and shorter daylight hours set the stage for winter.Temperature
In September, the average high-temperature registers at a still warm 80.8°F (27.1°C), nearly identical to August's 85.6°F (29.8°C). In the month of September, Marion witnesses a consistent average low-temperature of 60.4°F (15.8°C).Heat index
Throughout September, the heat index is estimated at 84.2°F (29°C). Exposure and extended activity could potentially cause a state of fatigue and lead to heat cramps.Observations indicate that the heat index values are for shady locations with light wind. Exposure to the sun directly might heighten the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'feels like', is a calculation that merges air temperature and relative humidity to depict the sensation of warmth. The effect is experienced differently by individuals, hinging on unique characteristics such as body mass, stature, and level of activity. Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely vital to babies and toddlers. Children often miss understanding the importance of rest and rehydration. Thirst usually appears late during dehydration - therefore, maintaining hydration, particularly during long physical activities, is essential.
Humidity
In September, the average relative humidity is 73%.Rainfall
The month with the least rainfall is September, when the rain falls for 10.5 days and typically collects 1.1" (28mm) of precipitation.Snowfall
In Marion, snow does not fall in May through September.Daylight
The average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:26 am and sunset at 7:24 pm. On the last day of September, sunrise is at 6:51 am and sunset at 6:39 pm CDT.
Sunshine
The average sunshine in September is 9.3h.UV index
In September, the average daily maximum UV index is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for the average person.Note: In September, the maximum UV index of 5 translates into these guidelines:
Take necessary precautions - Defending against sun damage is advocated. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. Employ a wide-brim hat for potent defense against up to 50% of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Marion, IL
- Average high temperature in September: 80.8°F
The warmest month (with the highest average high temperature) is July (87.4°F).
The month with the lowest average high temperature is January (39.6°F).
- Average low temperature in September: 60.4°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (26.1°F).
Average pressure in September
Marion, 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 (29.94"Hg).
Average wind speed in September
Marion, IL
- Average wind speed in September: 6.3mph
The windiest months (with the highest average wind speed) are January and February (9.4mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).
Average humidity in September
Marion, IL
- Average humidity in September: 73%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Marion, IL
- Average rainfall in September: 1.1"
The wettest month (with the highest rainfall) is April (3.11").
The driest month (with the least rainfall) is September (1.1").
Average rainfall days in September
Marion, IL
- Average rainfall days in September: 10.5 days
The month with the highest number of rainy days is July (15.3 days).
The month with the least rainy days is November (7.8 days).
Average snowfall in September
Marion, IL
- Average snowfall in September: 0"
The months with the highest snowfall are January and February (0.94").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Marion, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (4.3 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
Marion, IL
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 9h and 18min
The months with the most sunshine are June and July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in September
Marion, IL
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is October (20.6 days).
The month with the least sunshine days is July (12.9 days).
Average UV index in September
Marion, IL
- Average UV index in September: 5
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February and December (UV index 2).
Average cloud cover in September
Marion, IL
- Average cloud cover in September: 28
The month with the most cloud cover is February (Cloud cover 51).
The months with the least cloud cover are June, August and September (Cloud cover 28).
Average visibility in September
Marion, 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).
