August weather forecast
Decatur, IL

Weather in August

The last month of the summer, August, is also a moderately hot month in Decatur, Illinois, with temperature in the range of an average high of 81.1°F (27.3°C) and an average low of 63.9°F (17.7°C).

Temperature

In Decatur, the average high-temperature in August is relatively the same as in July - a still moderately hot 81.1°F (27.3°C). In Decatur, Illinois,, the average low-temperature is 63.9°F (17.7°C).

Heat index

In August, the average heat index is evaluated at a tropical 87.1°F (30.6°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.
Note that heat index values are valued for light wind and location in the shade. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like', 'apparent temperature', 'real feel', or 'felt air temperature', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. This effect is individual, with diverse people perceiving weather differently for numerous reasons (clothing, differences in body mass, height, and shape, metabolic differences), and activity. Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

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

Rainfall

In Decatur, during 11.8 rainfall days, 1.5" (38mm) of precipitation is typically accumulated. Throughout the year, in Decatur, Illinois, there are 130.2 rainfall days, and 16.34" (415mm) of precipitation is accumulated.

Snowfall

In Decatur snow does not fall in May through October.

Daylight

The average length of the day in August is 13.7h.

Sunshine

The average sunshine in Decatur is 9.9h.

UV index

Months with the highest UV index in Decatur are June through August, with an average maximum UV index of 6. A UV Index estimate of 6 to 7 represents a high health vulnerability from unprotected exposure to the Sun's UV rays for ordinary individuals.
Note: The average daily UV index of 6 in August transform into the following instructions:
Take precautions against overexposure. Protection against sun damage is needed. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun 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.
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FAQ

What is the temperature in August in Decatur?

In Decatur, Illinois, in August, the average high-temperature is 81.1°F (27.3°C), and the average low-temperature is 63.9°F (17.7°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), which factors the actual air temperature with the relative humidity, in August is evaluated at 87.1°F (30.6°C).

What is the average humidity in August in Decatur?

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

How much does it rain in Decatur in August?

In Decatur, during August, the rain falls for 11.8 days and regularly aggregates up to 1.5" (38mm) of precipitation.

When it does not snow in Decatur?

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

How many hours of daylight does Decatur have in August?

In August, the average length of the day is 13.7h.

How many hours of sunshine does Decatur have in August?

In August, the average sunshine in Decatur, Illinois, is 9.9h.

What is the month with the highest UV index in Decatur?

Months with the highest UV index in Decatur, Illinois, are June through August, with an average maximum UV index of 6.

What is the UV index intensity in August in Decatur?

The average daily maximum UV index in August in Decatur is 6. A UV Index estimate of 6 to 7 represents a high hazard to health from the exposure to the Sun's UV radiation.

Average temperature in August
Decatur, IL

Average temperature in August - Decatur, IL
  • Average high temperature in August: 81.1°F

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (32.9°F).

  • Average low temperature in August: 63.9°F

The month with the highest average low temperature is July (65.7°F).
The coldest month (with the lowest average low temperature) is January (21.2°F).

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Average pressure in August
Decatur, IL

Average pressure in August - Decatur, IL
  • Average pressure in August: 29.98"

The month with the highest atmospheric pressure is January (30.15").
The month with the lowest atmospheric pressure is June (29.92").

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Average wind speed in August
Decatur, IL

Average wind speed in August - Decatur, IL
  • Average wind speed in August: 6.3mph

The windiest month (with the highest average wind speed) is January (10.7mph).
The calmest months (with the lowest average wind speed) are July and August (6.3mph).

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Average humidity in August
Decatur, IL

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

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 August
Decatur, IL

Average rainfall in August - Decatur, IL
  • Average rainfall in August: 1.5"

The wettest month (with the highest rainfall) is May (2.01").
The driest months (with the least rainfall) are February and December (0.87").

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Average rainfall days in August
Decatur, IL

Average rainfall days in August - Decatur, IL
  • Average rainfall days in August: 11.8 days

The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is February (5.8 days).

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Average snowfall in August
Decatur, IL

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

The month with the highest snowfall is January (1.85").
Months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in August
Decatur, IL

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

The month with the highest number of snowfall days is January (7.2 days).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

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

Average daylight in August / Average sunshine in August - Decatur, IL
  • Average daylight in August: 13.7h

The month with the longest days is June (Average daylight: 15h).
The month with the shortest days is December (Average daylight: 9.4h).

  • Average sunshine in August: 9.9h

The month with the most sunshine is June (Average sunshine: 10.4h).
The month with the least sunshine is January (Average sunshine: 4.1h).

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Average sunshine days in August
Decatur, IL

Average sunshine days in August - Decatur, IL
  • Average sunshine days in August: 16.6 days

The month with the most sunshine days is October (19.8 days).
The month with the least sunshine days is May (11.5 days).

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Average UV index in August
Decatur, IL

Average UV index in August - Decatur, IL
  • Average UV index in August: 6

Months with the highest UV index are June, July and August (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in August
Decatur, IL

Average cloud cover in August - Decatur, IL
  • Average cloud cover in August: 31

The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is September (Cloud cover 29).

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Average visibility in August
Decatur, IL

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

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

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