September weather forecastHarrisburg, IL
September
Weather in September
September in Harrisburg, Illinois marks the transition from Summer to Autumn, with temperatures fluctuating between 60.4°F (15.8°C) and 80.8°F (27.1°C). A noticeable relief from the high summer temperatures, September brings along cooler days and nights. The city undergoes a transformation with an assortment of colors, as leaves begin to turn. With rainfall drop to 1.57" (40mm), the lowest for the year, compared to the previous months, this month offers a comfortable balance of weather conditions. Gradually, the temperature keeps decreasing, setting the tone for the forthcoming Fall season.Temperature
Harrisburg records an average high-temperature of a still warm 80.8°F (27.1°C) in September, maintaining a close correlation with August's 85.6°F (29.8°C). Harrisburg experiences a consistent average temperature of 60.4°F (15.8°C) throughout the nights in September.Heat index
The heat index for September is evaluated at 84.2°F (29°C). Unrelenting activity during exposure could cause fatigue and potentially lead to heat cramps.For clarity, heat index numbers account for light winds and areas under shade. Exposure to the sun directly might heighten the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'feels like', blends air temperature and moisture content to represent the felt temperature to humans. An individual's perception of weather can be affected by a variety of elements including metabolic differences, being pregnant, and their level of physical exertion. When exposed to direct sunlight, it's possible for the heat index to increase by as much as 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Typically, young kids are at a higher risk than adults since they sweat less. Also, the larger skin surface in proportion to their small bodies and the heightened heat production due to their active nature adds to their vulnerability.
Humidity
In Harrisburg, the average relative humidity in September is 73%.Rainfall
September is the month with the least rainfall. Rain falls for 10.5 days and accumulates 1.57" (40mm) of precipitation.Snowfall
In Harrisburg, snow does not fall in May through September.Daylight
In Harrisburg, the average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:24 am and sunset at 7:22 pm. On the last day of September, sunrise is at 6:49 am and sunset at 6:38 pm CDT.
Sunshine
In September, the average sunshine is 9.2h.UV index
In Harrisburg, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from unprotected exposure to Sun's UV rays for average individuals.Note: In September, a daily UV index of 5 turns into the following recommendations:
Safety measures are advised. Light-skinned individuals may experience burns in under half an hour. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Enhance your sun protection with tightly woven, yet airy clothing.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Harrisburg, IL
- Average high temperature in September: 80.8°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 (39.7°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 (26.2°F).
Average pressure in September
Harrisburg, 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
Harrisburg, IL
- Average wind speed in September: 6.4mph
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
Harrisburg, 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 (70%).
Average rainfall in September
Harrisburg, IL
- Average rainfall in September: 1.57"
The wettest month (with the highest rainfall) is April (4.8").
The driest month (with the least rainfall) is September (1.57").
Average rainfall days in September
Harrisburg, IL
- Average rainfall days in September: 10.5 days
The month with the highest number of rainy days is May (18.5 days).
The month with the least rainy days is November (9.7 days).
Average snowfall in September
Harrisburg, IL
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.73").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Harrisburg, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (5.3 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
Harrisburg, 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 12min
The month with the most sunshine is June (Average sunshine: 10h and 36min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in September
Harrisburg, IL
- Average sunshine days in September: 17.1 days
The month with the most sunshine days is October (19.5 days).
The month with the least sunshine days is May (9.9 days).
Average UV index in September
Harrisburg, 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
Harrisburg, IL
- Average cloud cover in September: 28
The months with the most cloud cover are January and February (Cloud cover 51).
The months with the least cloud cover are June and September (Cloud cover 28).
Average visibility in September
Harrisburg, 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).
