August weather forecast
Joliet, IL

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A unique shot of cars, trees, and buildings along a street in the town of Joliet, Illinois
A unique shot of cars, trees, and buildings along a street in the town of Joliet, Illinois

Weather in August

August mirrors July in many ways, but with a subtle hint of upcoming autumn. The overall temperature marginally declines from July’s high of 81.3°F (27.4°C) to August’s 80.1°F (26.7°C). Extended sunlight hours and less wind activity continue to mark the weather pattern in August. Despite the lesser rainfall, humidity stays virtually unchanged, preserving the overall summer atmosphere.

Temperature

As August unfolds in Joliet, the average high-temperature reaches a still moderately hot 80.1°F (26.7°C), hinting at a slight fluctuation from the previous month. Joliet, during the nights of August, experiences an average temperature drop to a comfortable 62.8°F (17.1°C).

Humidity

In August, the average relative humidity in Joliet is 82%.

Rainfall

In Joliet, Illinois, during August, the rain falls for 15.8 days and regularly aggregates up to 2.83" (72mm) of precipitation. In Joliet, during the entire year, the rain falls for 153.6 days and collects up to 32.72" (831mm) of precipitation.

Snowfall

May through October are months without snowfall in Joliet.

Daylight

In Joliet, the average length of the day in August is 13h and 47min.
On the first day of August, sunrise is at 5:47 am and sunset at 8:09 pm. On the last day of the month, sunrise is at 6:18 am and sunset at 7:26 pm CDT.

Sunshine

The month with the most sunshine in Joliet is August, with an average of 9.7h of sunshine.

UV index

The average daily maximum UV index in August in Joliet is 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: In August, the UV index of 5 transforms into the following advice:
Heed the precautions - Suggestions to avoid sunburn are made. Sun's radiation is most powerful around mid-day, so it's best to limit outdoor activities during this time. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.
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Frequently asked questions

What is the usual temperature for Joliet in August?

An average high-temperature, in August, in Joliet, is 80.1°F (26.7°C) and the average low-temperature is 62.8°F (17.1°C). In July, the average heat index (a.k.a. 'apparent temperature', 'felt air temperature'), which factors the actual air temperature with the relative humidity, is calculated to be 87.8°F (31°C).

What is the average humidity in August in Joliet?

In Joliet, Illinois, the average relative humidity in August is 82%.

How many days does it rain in August in Joliet?

In Joliet, Illinois, in August, it is raining for 15.8 days, with typically 2.83" (72mm) of accumulated precipitation.

When it does not snow in Joliet?

In Joliet, Illinois, snow does not fall in May through October.

How many hours of daylight does Joliet have in August?

In Joliet, Illinois, the average day length in August is 13h and 47min.

What time are sunrise and sunset in August in Joliet?

In August, on the first day of the month, sunrise is at 5:47 am and sunset at 8:09 pm. On the last day of the month, sunrise is at 6:18 am and sunset at 7:26 pm CDT.

What month has the most sunshine in Joliet?

With an average of 9.7h of sunshine, August has the most sunshine of the year.

How long on average sun shines in August in Joliet?

In Joliet, the average sunshine duration in August is 9.7h.

How high is the UV index in August in Joliet?

In August, the average daily maximum UV index in Joliet, Illinois, is 5. A UV Index reading of 3 to 5 represents a moderate health threat from exposure to the Sun's 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 August
Joliet, IL

Average temperature in August - Joliet, IL
  • Average high temperature in August: 80.1°F

The warmest month (with the highest average high temperature) is July (81.3°F).
The month with the lowest average high temperature is January (29.3°F).

  • Average low temperature in August: 62.8°F

The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (17.4°F).

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Average pressure in August
Joliet, IL

Average pressure in August - Joliet, IL
  • Average pressure in August: 29.98"Hg

The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed in August
Joliet, IL

Average wind speed in August - Joliet, IL
  • Average wind speed in August: 5.9mph

The windiest month (with the highest average wind speed) is April (9.7mph).
The calmest month (with the lowest average wind speed) is August (5.9mph).

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Average humidity in August
Joliet, IL

Average humidity in August - Joliet, IL
  • Average humidity in August: 82%

The month with the highest relative humidity is February (83%).
The month with the lowest relative humidity is October (73%).

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Average rainfall in August
Joliet, IL

Average rainfall in August - Joliet, IL
  • Average rainfall in August: 2.83"

The wettest month (with the highest rainfall) is May (4.41").
The driest month (with the least rainfall) is February (1.61").

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Average rainfall days in August
Joliet, IL

Average rainfall days in August - Joliet, IL
  • Average rainfall days in August: 15.8 days

The month with the highest number of rainy days is July (17.9 days).
The month with the least rainy days is February (5.7 days).

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Average snowfall in August
Joliet, IL

Average snowfall in August - Joliet, IL
  • Average snowfall in August: 0"

The month with the highest snowfall is January (4.33").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in August
Joliet, IL

Average snowfall days in August - Joliet, IL
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is January (11.9 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

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Average daylight in August /
Average sunshine in August
Joliet, IL

Average daylight in August / Average sunshine in August - Joliet, IL
  • Average daylight in August: 13h and 5min

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).

  • Average sunshine in August: 9h and 4min

The month with the most sunshine is August (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

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Average sunshine days in August
Joliet, IL

Average sunshine days in August - Joliet, IL
  • Average sunshine days in August: 11.8 days

The month with the most sunshine days is November (18.1 days).
The month with the least sunshine days is June (10.4 days).

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Average UV index in August
Joliet, IL

Average UV index in August - Joliet, IL
  • Average UV index in August: 5

The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).

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Average cloud cover in August
Joliet, IL

Average cloud cover in August - Joliet, IL
  • Average cloud cover in August: 34

The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are August and September (Cloud cover 34).

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Average visibility in August
Joliet, IL

Average visibility in August - Joliet, IL
  • Average visibility in August: 5mi

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

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Joliet, Illinois, USA

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