September weather forecastJanesville, WI
September
Weather in September
September ushers in the subtly changing season from summer to autumn in Janesville, Wisconsin. Temperatures begin to cool, adding a fresh crispness to the city’s weather. The transition is marked by the leaves changing colors from green to vibrant hues of yellow, orange, and red. Rainfall experiences a noticeable decline to about 1.22" (31mm), a significant drop from the summer highs. September's weather endorses the onset of a picturesque autumn, celebrated with myriad local festivals, and the cityscape adorned in fall colors.Temperature
September heralds a minor drop in average high-temperature, sliding from August's moderately hot 78.1°F (25.6°C) to an agreeable 72.1°F (22.3°C). During the September nights, an average temperature of 53.1°F (11.7°C) is observed.Humidity
In September, the average relative humidity is 80%.Rainfall
In Janesville, in September, it is raining for 10.5 days, with typically 1.22" (31mm) of accumulated precipitation. Throughout the year, there are 127.7 rainfall days, and 17.87" (454mm) of precipitation is accumulated.Snowfall
In Janesville, snow does not fall in May through September.Daylight
The average length of the day in September is 12h and 29min.On the first day of the month, sunrise is at 6:21 am and sunset at 7:29 pm. On the last day of September, sunrise is at 6:53 am and sunset at 6:38 pm CDT.
Sunshine
In Janesville, the average sunshine in September is 8.5h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for the average person.Note: A daily high UV index of 4 in September leads to these guidelines:
Undertake protective steps - Recommendations to avoid sunburn are issued. When the Sun's UV radiation is most intense during midday, it's best to find shade and limit exposure. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Janesville, WI
- Average high temperature in September: 72.1°F
The warmest month (with the highest average high temperature) is July (79.7°F).
The month with the lowest average high temperature is January (25°F).
- Average low temperature in September: 53.1°F
The month with the highest average low temperature is July (62.4°F).
The coldest month (with the lowest average low temperature) is January (12.9°F).
Average pressure in September
Janesville, WI
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Janesville, WI
- Average wind speed in September: 7.3mph
The windiest month (with the highest average wind speed) is April (10.1mph).
The calmest month (with the lowest average wind speed) is August (6.4mph).
Average humidity in September
Janesville, WI
- Average humidity in September: 80%
The month with the highest relative humidity is January (87%).
The months with the lowest relative humidity are April and October (76%).
Average rainfall in September
Janesville, WI
- Average rainfall in September: 1.22"
The wettest month (with the highest rainfall) is June (2.76").
The driest months (with the least rainfall) are January and February (0.75").
Average rainfall days in September
Janesville, WI
- Average rainfall days in September: 10.5 days
The month with the highest number of rainy days is June (16.3 days).
The month with the least rainy days is January (3.5 days).
Average snowfall in September
Janesville, WI
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.83").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Janesville, WI
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (12.5 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Janesville, WI
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 8h and 30min
The months with the most sunshine are July and August (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 30min).
Average sunshine days in September
Janesville, WI
- Average sunshine days in September: 17.3 days
The month with the most sunshine days is November (19.1 days).
The month with the least sunshine days is June (10.9 days).
Average UV index in September
Janesville, WI
- Average UV index in September: 4
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Janesville, WI
- Average cloud cover in September: 34
The month with the most cloud cover is January (Cloud cover 64).
The month with the least cloud cover is September (Cloud cover 34).
Average visibility in September
Janesville, WI
- Average visibility in September: 5mi
The months with the highest visibility are March, April, May, June, October, November and December (6mi).
The months with the lowest visibility are January, February, July, August and September (5mi).
