September weather forecastHerrin, IL
September
Weather in September
September, the first month of the autumn in Herrin, is still a warm month, with an average temperature fluctuating between 60.4°F (15.8°C) and 80.8°F (27.1°C).Temperature
September's weather records an average high-temperature of a still warm 80.8°F (27.1°C), showing little deviation from August. In Herrin, the average nighttime temperature during September is a mild 60.4°F (15.8°C).Heat index
For September, the heat index is evaluated at 84.2°F (29°C). Unrelenting activity during exposure could cause fatigue and potentially lead to heat cramps.Take into consideration that the heat index values are calculated for shade and light wind conditions. With exposure to direct sunshine, the heat index could climb by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', marries air temperature and humidity to produce a value illustrating perceived warmth. Additional factors encompassing metabolic differences, the level of physical activity, and clothing can impact the individual's perception of temperature. Keep it in mind, direct sunlight can augment the heat you experience, possibly pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values hold particular significance for children. Youngsters are usually more at risk than adults, considering they sweat less. Additionally, their high skin surface area compared to their little bodies and their high heat production due to activity increases their risk.
Humidity
In September, the average relative humidity in Herrin is 73%.Rainfall
September is the month with the least rainfall in Herrin, Illinois. Rain falls for 10.5 days and accumulates 1.1" (28mm) of precipitation.Snowfall
May through September are months without snowfall.Daylight
In September, the average length of the day in Herrin is 12h and 25min.On the first day of the month, sunrise is at 6:26 am and sunset at 7:24 pm. On the last day of September, in Herrin, sunrise is at 6:51 am and sunset at 6:40 pm CDT.
Sunshine
In September, the average sunshine is 9.3h.UV index
In Herrin, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for the ordinary person.Note: The daily maximum UV index of 5 in September interprets into the following advice:
Be vigilant - Suggestions to stave off sun damage are provided. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. A wide-brimmed hat is a staple for defending the face, eyes, ears, and neck from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Herrin, IL
- Average high temperature in September: 80.8°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 September: 60.4°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 September
Herrin, IL
- Average pressure in September: 30.03"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 September
Herrin, IL
- Average wind speed in September: 6.3mph
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 September
Herrin, IL
- Average humidity in September: 73%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Herrin, IL
- Average rainfall in September: 1.1"
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 September
Herrin, IL
- Average rainfall days in September: 10.5 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 September
Herrin, IL
- Average snowfall in September: 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 September
Herrin, IL
- Average snowfall days in September: 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 September /
Average sunshine in September
Herrin, IL
- Average daylight in September: 12h and 24min
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 September: 9h 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 September
Herrin, IL
- Average sunshine days in September: 17.5 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 September
Herrin, IL
- Average UV index in September: 5
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 September
Herrin, IL
- Average cloud cover in September: 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 September
Herrin, IL
- Average visibility in September: 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).
