August weather forecastHerrin, IL
August
Weather in August
The last month of the summer, August, is also a moderately hot month in Herrin, Illinois, with an average temperature varying between 66.4°F (19.1°C) and 85.6°F (29.8°C).Temperature
The shift from July to August is characterized by an average high-temperature of a warm 85.6°F (29.8°C), not significantly different from the 87.4°F (30.8°C) of July. An average low-temperature of 66.4°F (19.1°C) is recorded during the nights in August.Heat index
For August, the heat index is evaluated at a torrid 96.8°F (36°C). Undertake enhanced precautions, heat exhaustion and heat cramps are possible risks. Continuous activity could trigger heatstroke.When assessing, remember that heat index measurements are for light winds and shaded spots. Heat index values may rise by up to 15 Fahrenheit (8 Celsius) degrees when exposed to direct sunlight.
Note: The heat index, also known as 'real feel' or 'felt air temperature', ties air temperature with relative humidity to produce the perceived temperature sensation. Metabolic differences, pregnancy status, and the level of physical activity are additional factors influencing an individual's weather perception. Do note, being directly under sun rays can amplify the heat you feel, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical for babies and toddlers. Kids frequently ignore the importance of taking a break and rehydrating. Thirst is a late symptom of dehydration - thus, it is crucial to stay hydrated, especially during long-lasting physical activities.
Sweat evaporation plays a crucial role in cooling the human body, a process enabled by perspiration. Heightened relative humidity interferes with the body's usual cooling mechanism by reducing evaporation, subsequently decreasing the body's cooling rate and increasing the sensation of heat. Accumulating more heat than the body can dissipate leads to an uptick in body temperature, with potential heat stress consequences.
Humidity
The average relative humidity in August in Herrin is 76%.Rainfall
In August, in Herrin, the rain falls for 13.5 days. Throughout August, 1.89" (48mm) of precipitation is accumulated. Throughout the year, in Herrin, Illinois, there are 137.6 rainfall days, and 23.03" (585mm) of precipitation is accumulated.Snowfall
In Herrin, snow does not fall in May through September.Daylight
In Herrin, the average length of the day in August is 13h and 35min.On the first day of the month, sunrise is at 6:00 am and sunset at 8:04 pm. On the last day of August, sunrise is at 6:25 am and sunset at 7:26 pm CDT.
Sunshine
In August, the average sunshine is 10.3h.UV index
May 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 health hazard from unsafe exposure to UV radiation for the average person.Note: The UV index of 6 during August translates into the following guidance:
Prevent overexposure. Protection from the sun's harmful effects is needed. To the best of your ability, limit your exposure to the sun between the hours of 10 a.m. and 4 p.m., when UV radiation is at its peak. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in August
Herrin, IL
- Average high temperature in August: 85.6°F
The warmest month (with the highest average high temperature) is July (87.4°F).
The month with the lowest average high temperature is January (39.6°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
Herrin, 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
Herrin, IL
- Average wind speed in August: 5.8mph
The windiest months (with the highest average wind speed) are January and February (9.4mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).
Average humidity in August
Herrin, 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 (71%).
Average rainfall in August
Herrin, IL
- Average rainfall in August: 1.89"
The wettest month (with the highest rainfall) is April (3.11").
The driest month (with the least rainfall) is September (1.1").
Average rainfall days in August
Herrin, IL
- Average rainfall days in August: 13.5 days
The month with the highest number of rainy days is July (15.3 days).
The month with the least rainy days is November (7.8 days).
Average snowfall in August
Herrin, IL
- Average snowfall in August: 0"
The months with the highest snowfall are January and February (0.94").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in August
Herrin, IL
- Average snowfall days in August: 0 days
The month with the highest number of snowfall days is February (4.3 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
Herrin, 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 18min
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
Herrin, IL
- Average sunshine days in August: 14.9 days
The month with the most sunshine days is October (20.6 days).
The month with the least sunshine days is July (12.9 days).
Average UV index in August
Herrin, 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
Herrin, IL
- Average cloud cover in August: 28
The month with the most cloud cover is February (Cloud cover 51).
The months with the least cloud cover are June, August and September (Cloud cover 28).
Average visibility in August
Herrin, 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).





