September weather forecast
Petersburg, IL

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Weather in September

September, the first month of the autumn in Petersburg, is still a warm month, with an average temperature fluctuating between 77.4°F (25.2°C) and 58.5°F (14.7°C).

Temperature

The arrival of September sees a recorded average high-temperature of a still moderately hot 77.4°F (25.2°C), showing little divergence from the previous month's conditions. The average temperature during September nights is registered at a mild 58.5°F (14.7°C).

Humidity

In September, the average relative humidity is 75%.

Rainfall

In Petersburg, during September, the rain falls for 11.9 days and regularly aggregates up to 2.87" (73mm) of precipitation. In Petersburg, during the entire year, the rain falls for 146.4 days and collects up to 30.67" (779mm) of precipitation.

Snowfall

In Petersburg, snow does not fall in May through September.

Daylight

The average length of the day in September in Petersburg is 12h and 26min.
On the first day of September in Petersburg, sunrise is at 6:27 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 6:42 pm CDT.

Sunshine

The average sunshine in September in Petersburg is 9.1h.

UV index

In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for the average person.
Note: The UV index of 5 during September leads to these advisories:
Exercise prudence. Persons with fair skin could be burned in under 30 minutes. UV radiation from the Sun is most dangerous during midday; take precautions and seek shade. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly.
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Frequently asked questions

What is the temperature in September in Petersburg?

Petersburg in September has an average high-temperature of 77.4°F (25.2°C) and an average low-temperature of 58.5°F (14.7°C). In August, the average heat index (a.k.a. 'apparent temperature', 'feels like'), which takes the relative humidity and factors it into the air temperature reading, is computed to be 89.6°F (32°C).

What is the average humidity in September in Petersburg?

The average relative humidity in September in Petersburg, Illinois, is 75%.

How many days does it rain in September in Petersburg?

In Petersburg, Illinois, in September, it is raining for 11.9 days, with typically 2.87" (73mm) of accumulated precipitation.

When it does not snow in Petersburg?

May through September are months without snowfall in Petersburg.

Does it snow in Petersburg in September?

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

How many hours of daylight does Petersburg have in September?

In September, the average day length is 12h and 26min.

When are sunrise and sunset in September in Petersburg?

In September, on the first day of the month, sunrise is at 6:27 am and sunset at 7:30 pm. On the last day of the month, in Petersburg, Illinois, sunrise is at 6:55 am and sunset at 6:42 pm CDT.

How long on average sun shines in September in Petersburg?

The average sunshine duration in September is 9.1h.

How high is the UV index in September in Petersburg?

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

Average temperature in September - Petersburg, IL
  • Average high temperature in September: 77.4°F

The warmest month (with the highest average high temperature) is July (82.8°F).
The month with the lowest average high temperature is January (32.9°F).

  • Average low temperature in September: 58.5°F

The month with the highest average low temperature is July (66°F).
The coldest month (with the lowest average low temperature) is January (20.7°F).

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Average pressure in September
Petersburg, IL

Average pressure in September - Petersburg, IL
  • Average pressure in September: 30.02"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed in September
Petersburg, IL

Average wind speed in September - Petersburg, IL
  • Average wind speed in September: 7.2mph

The windiest months (with the highest average wind speed) are January, February and April (10.3mph).
The calmest months (with the lowest average wind speed) are July and August (6.3mph).

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Average humidity in September
Petersburg, IL

Average humidity in September - Petersburg, IL
  • Average humidity in September: 75%

The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).

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Average rainfall in September
Petersburg, IL

Average rainfall in September - Petersburg, IL
  • Average rainfall in September: 2.87"

The wettest month (with the highest rainfall) is May (3.82").
The driest month (with the least rainfall) is December (1.5").

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Average rainfall days in September
Petersburg, IL

Average rainfall days in September - Petersburg, IL
  • Average rainfall days in September: 11.9 days

The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is February (6.2 days).

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Average snowfall in September
Petersburg, IL

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

The month with the highest snowfall is January (4.02").
The months with the least snowfall are May, June, July, August and September (0").

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Average snowfall days in September
Petersburg, IL

Average snowfall days in September - Petersburg, IL
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (10.3 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
Petersburg, IL

Average daylight in September / Average sunshine in September - Petersburg, IL
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).

  • Average sunshine in September: 9h and 1min

The month with the most sunshine is June (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).

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Average sunshine days in September
Petersburg, IL

Average sunshine days in September - Petersburg, IL
  • Average sunshine days in September: 16.1 days

The month with the most sunshine days is November (18.5 days).
The month with the least sunshine days is May (11.3 days).

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Average UV index in September
Petersburg, IL

Average UV index in September - Petersburg, 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).

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Average cloud cover in September
Petersburg, IL

Average cloud cover in September - Petersburg, IL
  • Average cloud cover in September: 31

The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is August (Cloud cover 30).

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Average visibility in September
Petersburg, IL

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

The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).

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Petersburg, Illinois, USA

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