August weather forecastJohnston City, IL
August
Weather in August
August, the last month of the summer in Johnston City, is also a moderately hot month, with an average temperature varying between 85.5°F (29.7°C) and 66.4°F (19.1°C).Temperature
The arrival of August brings an average high-temperature of a moderately hot 85.5°F (29.7°C), nearly identical to July's 87.3°F (30.7°C). August nights in Johnston City, Illinois, cool down to an average low-temperature of 66.4°F (19.1°C).Heat index
August's mean heat index is calculated to be a torrid 96.8°F (36°C). Implement heightened safety measures - risk of heat exhaustion and heat cramps is increased. Prolonged activity may result in heatstroke.Remember that heat index calculations are made for conditions in the shade with light wind. Direct sunlight exposure may cause a 15 Fahrenheit (8 Celsius) degrees rise in the heat index.
Note: The heat index, also known as 'apparent temperature' or 'real feel', comes about by integrating the temperature readings with the humidity levels. The experience of temperature can be subjective, varying based on the individual's activity and heat perception, influenced by factors like wind, attire, and metabolic variations. When in direct sunlight, one should be cautious as it can raise the heat index by as much as 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical to babies and toddlers. Children often overlook the need for breaks and fluid intake. Thirst is a late-stage sign of dehydration - hence, it is necessary to stay hydrated, especially during extended periods of physical activities.
Sweat evaporation, driven by perspiration, is the method the human body uses to rid itself of excessive warmth. Under conditions of increased relative humidity, the evaporation rate lessens, causing the body to retain more heat than under less humid conditions. Heat absorption that surpasses the body's shedding capability can lead to overheating and varying levels of dehydration.
Humidity
In August, the average relative humidity is 76%.Rainfall
In Johnston City, in August, it is raining for 15.7 days, with typically 3.15" (80mm) of accumulated precipitation. In Johnston City, during the entire year, the rain falls for 167.2 days and collects up to 37.68" (957mm) of precipitation.Snowfall
In Johnston City, snow does not fall in May through September.Daylight
The average length of the day in August in Johnston City, Illinois, is 13h and 35min.On the first day of August, sunrise is at 5:59 am and sunset at 8:04 pm. On the last day of the month, sunrise is at 6:25 am and sunset at 7:26 pm CDT.
Sunshine
In Johnston City, the average sunshine in August is 10.2h.UV index
The months with the highest UV index in Johnston City are May through August, with an average maximum UV index of 6. A UV Index of 6 to 7 symbolizes a high threat to health from exposure to the Sun's UV radiation for the ordinary person.Note: The UV index of 6 in August translates into these instructions:
Inhibit overexposure. Warding off sun damage is of utmost importance. Between 10 a.m. and 4 p.m., the Sun emits the most powerful UV radiation. Limit direct exposure to the Sun during these hours. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in August
Johnston City, IL
- Average high temperature in August: 85.5°F
The warmest month (with the highest average high temperature) is July (87.3°F).
The month with the lowest average high temperature is January (39°F).
- Average low temperature in August: 66.4°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (26.1°F).
Average pressure in August
Johnston City, 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 (29.94"Hg).
Average wind speed in August
Johnston City, IL
- Average wind speed in August: 5.8mph
The windiest months (with the highest average wind speed) are January and February (9.6mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).
Average humidity in August
Johnston City, IL
- Average humidity in August: 76%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (70%).
Average rainfall in August
Johnston City, IL
- Average rainfall in August: 3.15"
The wettest month (with the highest rainfall) is April (4.92").
The driest month (with the least rainfall) is September (1.97").
Average rainfall days in August
Johnston City, IL
- Average rainfall days in August: 15.7 days
The month with the highest number of rainy days is May (18.5 days).
The month with the least rainy days is January (9.7 days).
Average snowfall in August
Johnston City, IL
- Average snowfall in August: 0"
The month with the highest snowfall is February (1.93").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in August
Johnston City, IL
- Average snowfall days in August: 0 days
The month with the highest number of snowfall days is January (6.1 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
Johnston City, IL
- Average daylight in August: 13h and 36min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in August: 10h and 12min
The months with the most sunshine are June and July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in August
Johnston City, IL
- Average sunshine days in August: 12.3 days
The month with the most sunshine days is October (17.6 days).
The month with the least sunshine days is June (9.9 days).
Average UV index in August
Johnston City, 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 and December (UV index 2).
Average cloud cover in August
Johnston City, IL
- Average cloud cover in August: 29
The month with the most cloud cover is February (Cloud cover 51).
The month with the least cloud cover is June (Cloud cover 28).
Average visibility in August
Johnston City, 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).
