Contents
- Weather in August
- Frequently asked questions
- Average temperature in August
- Average pressure in August
- Average wind speed in August
- Average humidity in August
- Average rainfall in August
- Average rainfall days in August
- Average snowfall in August
- Average snowfall days in August
- Average daylight in August
- Average sunshine in August
- Average sunshine days in August
- Average UV index in August
- Average cloud cover in August
- Average visibility in August
Weather in August
Temperature
O'Fallon experiences a minor change to a still warm 84.2°F (29°C) in average high-temperature during August, closely reflecting July. Nighttime temperatures hover around an average low of 66°F (18.9°C) in August.Heat index
For August, the heat index is appraised at a very hot 95°F (35°C). Implement enhanced safety actions, heat cramps and heat exhaustion could occur. Sustained activity might result in heatstroke.One should be cognizant that the heat index values are tailored for shaded spots and mild winds. The heat index could experience an increase of 15 Fahrenheit (8 Celsius) degrees due to direct sunlight.
Note: The heat index, also known as 'apparent temperature' or 'feels like', combines both the air temperature and the humidity level to give a perceived human temperature. The individual's impression of temperature can be shaped by additional aspects such as metabolic variations, physical activity, and clothing. Understand that direct sun rays can influence the weather's impact, leading to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values hold great significance to children. Young ones often underestimate the need for rest and rehydration. Thirst appears late in dehydration - hence, it is important to keep hydrated, particularly during prolonged physical activities.
The innate cooling system of the human body revolves around perspiration, with the evaporation of sweat being central to this process. Under high air temperature and humidity (high heat index) conditions, perspiration is limited, and the perception of heat is increased. Heat-related complications, like dehydration, can manifest if the body's heat gain exceeds its dissipation capacity.
Humidity
May, July and August, with an average relative humidity of 79%, are the most humid months.Rainfall
In O'Fallon, during August, the rain falls for 11.1 days and regularly aggregates up to 1.26" (32mm) of precipitation. Throughout the year, in O'Fallon, there are 108.8 rainfall days, and 10.24" (260mm) of precipitation is accumulated.Snowfall
In O'Fallon, snow does not fall in April through October.Daylight
In August, the average length of the day is 13h and 37min.On the first day of August, sunrise is at 6:02 am and sunset at 8:09 pm. On the last day of the month, sunrise is at 6:28 am and sunset at 7:30 pm CDT.
Sunshine
The average sunshine in August 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 unsafe exposure to UV radiation for the average person.Note: An average UV index of 6 in August transforms into this advice:
Uphold preventive measures and conform to sun safety guidelines. Defending against skin and eye harm is crucial. Seek shade and limit direct sun exposure between 10 a.m. and 4 p.m., the peak period for UV radiation. Keep in mind that shade structures like parasols or canopies do not offer complete sun protection. Shield yourself from the harmful effects of UV radiation with sun-protective attire, a hat, and quality sunglasses.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot is August?
What is the most humid month?
What is the average humidity in August in O'Fallon?
How much does it rain in O'Fallon in August?
When it does not snow?
What is the average length of the day in August?
When is the sunrise / sunset in August?
How long on average sun shines in August?
What is the month with the highest UV index?
How high is the UV index in August?
Average temperature in August
O'Fallon, IL
- Average high temperature in August: 84.2°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 (37.8°F).
- Average low temperature in August: 66°F
The month with the highest average low temperature is July (68.2°F).
The coldest month (with the lowest average low temperature) is January (24.6°F).
Average pressure in August
O'Fallon, 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
O'Fallon, IL
- Average wind speed in August: 5.7mph
The windiest month (with the highest average wind speed) is January (9.5mph).
The calmest month (with the lowest average wind speed) is July (5.6mph).
Average humidity in August
O'Fallon, IL
- Average humidity in August: 79%
The months with the highest relative humidity are May, July and August (79%).
The month with the lowest relative humidity is October (70%).
Average rainfall in August
O'Fallon, IL
- Average rainfall in August: 1.26"
The wettest month (with the highest rainfall) is July (1.42").
The driest month (with the least rainfall) is December (0.31").
Average rainfall days in August
O'Fallon, IL
- Average rainfall days in August: 11.1 days
The month with the highest number of rainy days is July (13.1 days).
The month with the least rainy days is December (4.6 days).
Average snowfall in August
O'Fallon, IL
- Average snowfall in August: 0"
The month with the highest snowfall is January (0.51").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in August
O'Fallon, IL
- Average snowfall days in August: 0 days
The month with the highest number of snowfall days is January (4.7 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
O'Fallon, 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 30min).
- Average sunshine in August: 10h and 1min
The months with the most sunshine are June and July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).
Average sunshine days in August
O'Fallon, IL
- Average sunshine days in August: 18 days
The month with the most sunshine days is December (23.6 days).
The months with the least sunshine days are May and July (15.5 days).
Average UV index in August
O'Fallon, 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, February, November and December (UV index 2).
Average cloud cover in August
O'Fallon, 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 August (Cloud cover 28).
Average visibility in August
O'Fallon, 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).
O'Fallon, Illinois, USA
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