September weather forecast and climate
Marion, IL

Weather in September

The first month of the autumn, September, is also a moderately hot month in Marion, Illinois, with temperature in the range of an average low of 60.4°F (15.8°C) and an average high of 80.8°F (27.1°C).

Temperature

In Marion, the average high-temperature in September is practically the same as in August - a still moderately hot 80.8°F (27.1°C). In September, the average low-temperature is 60.4°F (15.8°C).

Heat index

The average heat index is calculated to be 84.7°F (29.3°C). Exhaustion is likely with prolonged exposure and activity. Sustaining activity may result in heat cramps.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature', 'felt air temperature', 'feels like', or 'real feel', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. Additional factors like activity, pregnancy, differences in body mass, height, and shape, and metabolic differences affect individual temperature impact. Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.

Humidity

In Marion, 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

May through September are months without snowfall.

Daylight

In Marion, the average length of the day is 12.4h.

Sunshine

The average sunshine in September is 9.3h.

UV index

In Marion, Illinois, the average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium health hazard from the exposure to the Sun's UV rays for the ordinary person.
Note: The daily maximum UV index of 5 interpret into the following advice:
Take precautions - Protection against sunburn is recommended. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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FAQ

What is the temperature in September in Marion?

The average high-temperature, in September, in Marion, is 80.8°F (27.1°C), while the average low-temperature is 60.4°F (15.8°C). In September, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which factors the actual air temperature with the relative humidity, is calculated to be 84.7°F (29.3°C).

What is the average humidity in September in Marion?

The average relative humidity in September is 73%.

What is the driest month in Marion?

September is the month with the least rainfall. Rain falls for 10.5 days and accumulates 1.1" (28mm) of precipitation.

How many days does it rain in September in Marion?

In Marion, Illinois, in September, during 10.5 rainfall days, 1.1" (28mm) of precipitation is typically accumulated.

When it does not snow in Marion?

May through September are months without snowfall in Marion.

Does it snow in Marion in September?

In Marion, in September, it doesn't snow. In October, it regularly snows.

How many hours of daylight does Marion have in September?

In September, the average length of the day in Marion is 12.4h.

How long on average sun shines in September in Marion?

The average sunshine in September in Marion is 9.3h.

What is the UV index reading in September in Marion?

The average daily maximum UV index in September in Marion, Illinois, is 5. A UV Index value of 3 to 5 symbolizes a medium hazard to health from unsafe exposure to the Sun's UV rays.

Average temperature in September
Marion, IL

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).

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Average pressure in September
Marion, IL

Average pressure in September - Marion, IL
  • Average pressure in September: 30.03"

The month with the highest atmospheric pressure is January (30.16").
The month with the lowest atmospheric pressure is June (29.94").

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Average wind speed in September
Marion, IL

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).

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Average humidity in September
Marion, IL

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%).

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Average rainfall in September
Marion, IL

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").

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Average rainfall days in September
Marion, IL

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).

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Average snowfall in September
Marion, IL

Average snowfall in September - Marion, IL
  • Average snowfall in September: 0"

Months with the highest snowfall are January and February (0.94").
Months with the least snowfall are May, June, July, August and September (0").

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Average snowfall days in September
Marion, IL

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).
Months with the least snowfall days are May, June, July, August and September (0 days).

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Average daylight in September /
Average sunshine in September
Marion, IL

Average daylight in September / Average sunshine in September - Marion, IL
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.7h).
The month with the shortest days is December (Average daylight: 9.6h).

  • Average sunshine in September: 9.3h

Months with the most sunshine are June and July (Average sunshine: 10.5h).
The month with the least sunshine is January (Average sunshine: 4.6h).

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Average sunshine days in September
Marion, IL

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).

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Average UV index in September
Marion, IL

Average UV index in September - Marion, IL
  • Average UV index in September: 5

Months with the highest UV index are May, June, July and August (UV index 6).
Months with the lowest UV index are January, February and December (UV index 2).

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Average cloud cover in September
Marion, IL

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).
Months with the least cloud cover are June, August and September (Cloud cover 28).

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Average visibility in September
Marion, IL

Average visibility in September - Marion, IL
  • Average visibility in September: 6mi

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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