August weather forecast
Mount Vernon, IL

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Weather in August

August, the last month of the summer in Mount Vernon, is also a moderately hot month, with an average temperature fluctuating between 65.8°F (18.8°C) and 84°F (28.9°C).

Temperature

The commencement of August brings an average high-temperature of a still warm 84°F (28.9°C), marking an inconsequential divergence from July. August nights cool down to an average low-temperature of 65.8°F (18.8°C).

Heat index

August's average heat index is evaluated at a hot 93.2°F (34°C). Implement enhanced safety actions, heat cramps and heat exhaustion could occur. Sustained activity might result in heatstroke.
It is important to note that the heat index values are for shaded areas and light wind scenarios. Direct exposure to sunshine could lead to a heat index increase by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', embodies the combination of air temperature and moisture content to illustrate perceived heat. Additional elements encompassing metabolic differences, the degree of physical activity, and attire can impact the individual's perception of temperature. Under direct sun rays, the felt temperature might be heightened, with the heat index increasing by 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Young individuals usually face greater risks than adults as their sweat production is less. Also, their larger skin surface relative to their small bodies and the high heat generation due to their activity contributes to their vulnerability.

Humidity

The average relative humidity in August in Mount Vernon is 78%.

Rainfall

In August, in Mount Vernon, the rain falls for 13.4 days. Throughout August, 2.36" (60mm) of precipitation is accumulated. In Mount Vernon, during the entire year, the rain falls for 145.8 days and collects up to 29.13" (740mm) of precipitation.

Snowfall

In Mount Vernon, snow does not fall in May through October.

Daylight

In Mount Vernon, Illinois, the average length of the day in August is 13h and 37min.
On the first day of August in Mount Vernon, sunrise is at 5:58 am and sunset at 8:05 pm. On the last day of the month, sunrise is at 6:24 am and sunset at 7:26 pm CDT.

Sunshine

The average sunshine in August in Mount Vernon is 10.2h.

UV index

The months with the highest UV index are May through August, with an average maximum UV index of 6. A UV Index reading of 6 to 7 represents a high health risk from unprotected exposure to Sun's UV rays for the average person.
Note: A daily high UV index of 6 in August leads to these guidelines:
Beware of overexposure. Fair-skinned individuals risk burning in less than 20 minutes. UV radiation from the Sun is most intense between 10 a.m. and 4 p.m. Try to avoid direct sunlight during this period. Limit sun-induced ocular harm with sunglasses that feature UVA and UVB filtration.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How hot is it in Mount Vernon in August?

During August, Mount Vernon experiences an average high-temperature of 84°F (28.9°C) and a low-temperature of 65.8°F (18.8°C). The average heat index (a.k.a. 'feels like', 'felt air temperature'), which takes the relative humidity and factors it into the air temperature reading, in August is evaluated at 93.2°F (34°C).

What is the average humidity in August in Mount Vernon?

In Mount Vernon, Illinois, the average relative humidity in August is 78%.

How many days does it rain in August in Mount Vernon?

In August, the rain falls for 13.4 days. Throughout August, 2.36" (60mm) of precipitation is accumulated.

When it does not snow in Mount Vernon?

May through October are months without snowfall.

What is the average length of the day in August in Mount Vernon?

In August, the average day length in Mount Vernon, Illinois, is 13h and 37min.

When are sunrise and sunset in August in Mount Vernon?

On the first day of August in Mount Vernon, sunrise is at 5:58 am and sunset at 8:05 pm. On the last day of the month, sunrise is at 6:24 am and sunset at 7:26 pm CDT.

How many hours of sunshine does Mount Vernon have in August?

In August, the average sunshine duration in Mount Vernon is 10.2h.

What is the month with the highest UV index in Mount Vernon?

May through August, with an average maximum UV index of 6, are months with the highest UV index in Mount Vernon, Illinois.

What is the UV index reading in August in Mount Vernon?

In Mount Vernon, Illinois, the average daily maximum UV index in August is 6. A UV Index of 6 to 7 symbolizes a high 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 August
Mount Vernon, IL

Average temperature in August - Mount Vernon, IL
  • Average high temperature in August: 84°F

The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is January (37.9°F).

  • Average low temperature in August: 65.8°F

The month with the highest average low temperature is July (67.8°F).
The coldest month (with the lowest average low temperature) is January (24.8°F).

Average pressure in August
Mount Vernon, IL

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

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed in August
Mount Vernon, IL

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

The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest months (with the lowest average wind speed) are July and August (5.9mph).

Average humidity in August
Mount Vernon, IL

Average humidity in August - Mount Vernon, IL
  • Average humidity in August: 78%

The month with the highest relative humidity is May (80%).
The month with the lowest relative humidity is October (71%).

Average rainfall in August
Mount Vernon, IL

Average rainfall in August - Mount Vernon, IL
  • Average rainfall in August: 2.36"

The wettest month (with the highest rainfall) is April (3.78").
The driest month (with the least rainfall) is September (1.61").

Average rainfall days in August
Mount Vernon, IL

Average rainfall days in August - Mount Vernon, IL
  • Average rainfall days in August: 13.4 days

The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is January (7.5 days).

Average snowfall in August
Mount Vernon, IL

Average snowfall in August - Mount Vernon, IL
  • Average snowfall in August: 0"

The month with the highest snowfall is February (1.73").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days in August
Mount Vernon, IL

Average snowfall days in August - Mount Vernon, IL
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is January (4.8 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

Average daylight in August /
Average sunshine in August
Mount Vernon, IL

Average daylight in August / Average sunshine in August - Mount Vernon, IL
  • Average daylight in August: 13h and 4min

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 36min).

  • Average sunshine in August: 10h and 1min

The month with the most sunshine is June (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).

Average sunshine days in August
Mount Vernon, IL

Average sunshine days in August - Mount Vernon, IL
  • Average sunshine days in August: 15.6 days

The month with the most sunshine days is October (20.3 days).
The month with the least sunshine days is May (11.3 days).

Average UV index in August
Mount Vernon, IL

Average UV index in August - Mount Vernon, IL
  • Average UV index in August: 6

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, November and December (UV index 2).

Average cloud cover in August
Mount Vernon, IL

Average cloud cover in August - Mount Vernon, IL
  • Average cloud cover in August: 28

The month with the most cloud cover is January (Cloud cover 51).
The month with the least cloud cover is June (Cloud cover 27).

Average visibility in August
Mount Vernon, IL

Average visibility in August - Mount Vernon, 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).

Mount Vernon, Illinois, USA

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