September weather forecast
Saint Jacob, IL

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Weather in September

September, the first month of the autumn in Saint Jacob, is still a warm month, with temperature in the range of an average low of 59.7°F (15.4°C) and an average high of 78.1°F (25.6°C).

Temperature

September brings a slight decrease in temperature, down from a moderately hot 83.7°F (28.7°C) in August to a still warm 78.1°F (25.6°C). An average temperature of 59.7°F (15.4°C) is recorded during the nights in September.

Humidity

In Saint Jacob, the average relative humidity in September is 75%.

Rainfall

In Saint Jacob, Illinois, in September, during 9.5 rainfall days, 0.59" (15mm) of precipitation is typically accumulated. In Saint Jacob, Illinois, during the entire year, the rain falls for 110.6 days and collects up to 12.01" (305mm) of precipitation.

Snowfall

April through September are months without snowfall in Saint Jacob.

Daylight

In September, the average length of the day is 12h and 26min.
On the first day of the month, sunrise is at 6:28 am and sunset at 7:28 pm. On the last day of September, sunrise is at 6:54 am and sunset at 6:42 pm CDT.

Sunshine

The average sunshine in September in Saint Jacob is 9.5h.

UV index

In September, the average daily maximum UV index in Saint Jacob is 5. A UV Index reading of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV radiation for average individuals.
Note: A maximum high UV index of 5 in September translates into the following recommendations:
Act with care - The need to guard against sun damage is communicated. The solar radiation around mid-day is intense; avoid the Sun and stay safe. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days.
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Frequently asked questions

What are September temperatures in Saint Jacob?

In Saint Jacob, 78.1°F (25.6°C) is the average high-temperature and 59.7°F (15.4°C) is the average low-temperature during September. In August, the average heat index (a.k.a. 'real feel', 'apparent temperature'), which combines air temperature and relative humidity, is evaluated at 93.2°F (34°C).

What is the average humidity in September in Saint Jacob?

The average relative humidity in September is 75%.

How many days does it rain in September in Saint Jacob?

In Saint Jacob, Illinois, during September, the rain falls for 9.5 days and regularly aggregates up to 0.59" (15mm) of precipitation.

When it does not snow in Saint Jacob?

In Saint Jacob, snow does not fall in April through September.

Does it snow in Saint Jacob in September?

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

What is the average length of the day in September in Saint Jacob?

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

When is the sunrise / sunset in September in Saint Jacob?

In September, on the first day of the month, sunrise is at 6:28 am and sunset at 7:28 pm. On the last day of the month, in Saint Jacob, sunrise is at 6:54 am and sunset at 6:42 pm CDT.

How many hours of sunshine does Saint Jacob have in September?

In September, the average sunshine duration in Saint Jacob, Illinois, is 9.5h.

How high is the UV index in September in Saint Jacob?

In September, the average daily maximum UV index in Saint Jacob, Illinois, is 5. A UV Index value 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
Saint Jacob, IL

Average temperature in September - Saint Jacob, IL
  • Average high temperature in September: 78.1°F

The warmest month (with the highest average high temperature) is July (84.9°F).
The month with the lowest average high temperature is January (36.9°F).

  • Average low temperature in September: 59.7°F

The month with the highest average low temperature is July (67.6°F).
The coldest month (with the lowest average low temperature) is January (23.7°F).

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Average pressure in September
Saint Jacob, IL

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

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed in September
Saint Jacob, IL

Average wind speed in September - Saint Jacob, IL
  • Average wind speed in September: 6.2mph

The windiest month (with the highest average wind speed) is January (9.8mph).
The calmest months (with the lowest average wind speed) are July and August (5.7mph).

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Average humidity in September
Saint Jacob, IL

Average humidity in September - Saint Jacob, IL
  • Average humidity in September: 75%

The months with the highest relative humidity are July and August (80%).
The month with the lowest relative humidity is October (71%).

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Average rainfall in September
Saint Jacob, IL

Average rainfall in September - Saint Jacob, IL
  • Average rainfall in September: 0.59"

The wettest month (with the highest rainfall) is May (1.46").
The driest month (with the least rainfall) is February (0.55").

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Average rainfall days in September
Saint Jacob, IL

Average rainfall days in September - Saint Jacob, IL
  • Average rainfall days in September: 9.5 days

The month with the highest number of rainy days is May (13.1 days).
The months with the least rainy days are January and December (5.9 days).

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Average snowfall in September
Saint Jacob, IL

Average snowfall in September - Saint Jacob, IL
  • Average snowfall in September: 0"

The month with the highest snowfall is December (0.94").
The months with the least snowfall are April, May, June, July, August and September (0").

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Average snowfall days in September
Saint Jacob, IL

Average snowfall days in September - Saint Jacob, IL
  • Average snowfall days in September: 0 days

The months with the highest number of snowfall days are January and February (4.8 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
Saint Jacob, IL

Average daylight in September / Average sunshine in September - Saint Jacob, 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 30min).

  • Average sunshine in September: 9h and 3min

The month with the most sunshine is June (Average sunshine: 10h and 36min).
The months with the least sunshine are January and February (Average sunshine: 4h and 36min).

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Average sunshine days in September
Saint Jacob, IL

Average sunshine days in September - Saint Jacob, IL
  • Average sunshine days in September: 18.3 days

The month with the most sunshine days is December (21.8 days).
The month with the least sunshine days is July (14.5 days).

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Average UV index in September
Saint Jacob, IL

Average UV index in September - Saint Jacob, 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, November and December (UV index 2).

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Average cloud cover in September
Saint Jacob, IL

Average cloud cover in September - Saint Jacob, IL
  • Average cloud cover in September: 28

The months with the most cloud cover are January and February (Cloud cover 50).
The months with the least cloud cover are June, July, August and September (Cloud cover 28).

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Average visibility in September
Saint Jacob, IL

Average visibility in September - Saint Jacob, 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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Saint Jacob, Illinois, USA

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