September weather forecast
Marion, IL

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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

With the advent of September, Marion's high-temperatures adjust to a still warm 80.8°F (27.1°C), closely aligning with the preceding month. Throughout September, the average low-temperature in Marion records at a moderate 60.4°F (15.8°C).

Heat index

Throughout September, the heat index is calculated to be 84.2°F (29°C). Ongoing activity coupled with exposure often results in weariness and could induce heat cramps.
Metrics for the heat index primarily focus on shaded spots and light wind conditions. A direct sunlight exposure may boost the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'felt air temperature', is achieved by amalgamating air temperature with the relative humidity readings. A person's impression of weather can be shaped by many aspects, among them metabolic variations, pregnancy, and levels of physical activity. Always consider that direct sunlight exposure might heighten the heat's effects, pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values remain especially vital for babies and toddlers. Young individuals usually face more risks than adults due to their lower sweat production. Their large skin surface area relative to their tiny bodies and high heat production from their activities adds to their risk.

Humidity

In Marion, the average relative humidity in September is 73%.

Rainfall

The month with the least rainfall in Marion, Illinois, 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

In September, the average length of the day in Marion 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, in Marion, sunrise is at 6:51 am and sunset at 6:39 pm CDT.

Sunshine

In September, the average sunshine is 9.3h.

UV index

The average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for the ordinary person.
Note: An average maximum UV index of 5 in September leads to these recommendations:
Take heed. Individuals of lighter complexion can be burned in less than half an hour. When the Sun is at its strongest around midday, find shade and limit exposure. 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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Frequently asked questions

What are September temperatures in Marion?

The average high-temperature and low-temperature in Marion, Illinois, during September are 80.8°F (27.1°C) and 60.4°F (15.8°C) respectively. In September, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which takes the relative humidity and factors it into the air temperature reading, is calculated to be 84.2°F (29°C).

What is the average humidity in September in Marion?

The average relative humidity in September in Marion, Illinois, is 73%.

What is the driest month in Marion?

The month with the least rainfall in Marion is September, when the rain falls for 10.5 days and typically collects 1.1" (28mm) of precipitation.

How much does it rain in Marion in September?

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, Illinois.

Does it snow in Marion in September?

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

What is the average length of the day in September in Marion?

In September, the average day length in Marion, Illinois, is 12h and 25min.

When are sunrise and sunset in September in Marion?

In September, on the first day of the month, sunrise is at 6:26 am and sunset at 7:24 pm. On the last day of the month, in Marion, Illinois, sunrise is at 6:51 am and sunset at 6:39 pm CDT.

How long on average sun shines in September in Marion?

In Marion, the average sunshine duration in September is 9.3h.

What is the UV index reading in September in Marion?

In September, the average daily maximum UV index is 5. A UV Index value of 3 to 5 symbolizes a medium health risk from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

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"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).

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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"

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").

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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).
The 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: 12h and 2min

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 2min

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).

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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

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).

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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).
The 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

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).

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Marion, Illinois, USA

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