August weather forecast
Lake Forest, IL

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Weather in August

August, the last month of the summer in Lake Forest, is also a moderately hot month, with an average temperature ranging between max 77.5°F (25.3°C) and min 66.7°F (19.3°C).

Temperature

The arrival of August is marked by an average high-temperature of a still warm 77.5°F (25.3°C), bearing a close resemblance to July. Lake Forest reports a consistent average low-temperature of 66.7°F (19.3°C) throughout August nights.

Humidity

In August, the average relative humidity in Lake Forest is 76%.

Rainfall

In Lake Forest, in August, it is raining for 15.8 days, with typically 3.07" (78mm) of accumulated precipitation. In Lake Forest, during the entire year, the rain falls for 154.1 days and collects up to 30.24" (768mm) of precipitation.

Snowfall

May through September are months without snowfall.

Daylight

In Lake Forest, the average length of the day in August is 13h and 50min.
On the first day of the month, sunrise is at 5:45 am and sunset at 8:10 pm. On the last day of August, in Lake Forest, sunrise is at 6:16 am and sunset at 7:26 pm CDT.

Sunshine

With an average of 10.7h of sunshine, August has the most sunshine of the year in Lake Forest, Illinois.

UV index

June through August, with an average maximum UV index of 6, are months with the highest UV index. A UV Index reading of 6 to 7 represents a high threat to health from exposure to the Sun's UV radiation for average individuals.
Note: An average maximum UV index of 6 in August leads to these recommendations:
Implement precautions and maintain sun safety methods. Avoidance of sunburn is demanded. Stay in the shade and limit sun exposure from 10 a.m. to 4 p.m., when UV radiation is most potent. Keep in mind that shade structures like parasols or canopies do not offer full protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for Lake Forest in August?

The high-temperature in Lake Forest, Illinois, during August is 77.5°F (25.3°C) and the low-temperature is 66.7°F (19.3°C).

What is the average humidity in August in Lake Forest?

The average relative humidity in August is 76%.

How many days does it rain in August in Lake Forest?

In Lake Forest, Illinois, during August, the rain falls for 15.8 days and regularly aggregates up to 3.07" (78mm) of precipitation.

When it does not snow in Lake Forest?

May through September are months without snowfall in Lake Forest.

What is the average length of the day in August in Lake Forest?

In Lake Forest, the average day length in August is 13h and 50min.

When are sunrise and sunset in August in Lake Forest?

On the first day of August in Lake Forest, Illinois, sunrise is at 5:45 am and sunset at 8:10 pm. On the last day of the month, sunrise is at 6:16 am and sunset at 7:26 pm CDT.

What month has the most sunshine in Lake Forest?

The month with the most sunshine in Lake Forest is August, with an average of 10.7h of sunshine.

How long on average sun shines in August in Lake Forest?

In August, the average sunshine duration is 10.7h.

When is the highest UV index in Lake Forest?

The months with the highest UV index in Lake Forest, Illinois, are June through August, with an average maximum UV index of 6.

How high is the UV index in August in Lake Forest?

In August, the average daily maximum UV index is 6. A UV Index of 6 to 7 symbolizes a high 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
Lake Forest, IL

Average temperature in August - Lake Forest, IL
  • Average high temperature in August: 77.5°F

The warmest month (with the highest average high temperature) is July (77.7°F).
The month with the lowest average high temperature is January (28.6°F).

  • Average low temperature in August: 66.7°F

The months with the highest average low temperature are July and August (66.7°F).
The coldest month (with the lowest average low temperature) is January (18.9°F).

Average pressure in August
Lake Forest, IL

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

The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

Average wind speed in August
Lake Forest, IL

Average wind speed in August - Lake Forest, IL
  • Average wind speed in August: 7.4mph

The windiest month (with the highest average wind speed) is January (11.9mph).
The calmest month (with the lowest average wind speed) is August (7.4mph).

Average humidity in August
Lake Forest, IL

Average humidity in August - Lake Forest, IL
  • Average humidity in August: 76%

The months with the highest relative humidity are January and February (82%).
The month with the lowest relative humidity is October (73%).

Average rainfall in August
Lake Forest, IL

Average rainfall in August - Lake Forest, IL
  • Average rainfall in August: 3.07"

The wettest months (with the highest rainfall) are May and June (3.82").
The driest month (with the least rainfall) is December (1.3").

Average rainfall days in August
Lake Forest, IL

Average rainfall days in August - Lake Forest, IL
  • Average rainfall days in August: 15.8 days

The month with the highest number of rainy days is May (17.7 days).
The month with the least rainy days is February (5.9 days).

Average snowfall in August
Lake Forest, IL

Average snowfall in August - Lake Forest, IL
  • Average snowfall in August: 0"

The month with the highest snowfall is January (4.13").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days in August
Lake Forest, IL

Average snowfall days in August - Lake Forest, 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).

Average daylight in August /
Average sunshine in August
Lake Forest, IL

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

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

  • Average sunshine in August: 10h and 4min

The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).

Average sunshine days in August
Lake Forest, IL

Average sunshine days in August - Lake Forest, IL
  • Average sunshine days in August: 13.1 days

The month with the most sunshine days is December (15.3 days).
The month with the least sunshine days is April (10.8 days).

Average UV index in August
Lake Forest, IL

Average UV index in August - Lake Forest, IL
  • Average UV index in August: 6

The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).

Average cloud cover in August
Lake Forest, IL

Average cloud cover in August - Lake Forest, IL
  • Average cloud cover in August: 27

The month with the most cloud cover is January (Cloud cover 61).
The months with the least cloud cover are July and August (Cloud cover 27).

Average visibility in August
Lake Forest, IL

Average visibility in August - Lake Forest, IL
  • Average visibility in August: 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).

Lake Forest, Illinois, USA

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