Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The arrival of September marks a slight shift to an average high-temperature of a still moderately hot 77.4°F (25.2°C) from August's 81.9°F (27.7°C). An average low-temperature of 58.6°F (14.8°C) is recorded during the nights in September.Humidity
In September, the average relative humidity is 75%.Rainfall
In September, the rain falls for 12 days. Throughout September, 1.89" (48mm) of precipitation is accumulated. In Rochester, during the entire year, the rain falls for 141.7 days and collects up to 22.72" (577mm) of precipitation.Snowfall
In Rochester, snow does not fall in May through October.Daylight
The average length of the day in September is 12h and 26min.On the first day of the month, sunrise is at 6:26 am and sunset at 7:28 pm. On the last day of September, sunrise is at 6:54 am and sunset at 6:41 pm CDT.
Sunshine
In September, the average sunshine is 9.3h.UV index
In Rochester, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV rays for ordinary individuals.Note: In September, the maximum UV index of 5 transforms into these recommendations:
Undertake precautions - Obligation exists to protect against skin and eye damage. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
What is the average length of the day in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Rochester have in September?
How high is the UV index in September?
Average temperature in September
Rochester, IL
- Average high temperature in September: 77.4°F
The warmest month (with the highest average high temperature) is July (82.8°F).
The month with the lowest average high temperature is January (33.4°F).
- Average low temperature in September: 58.6°F
The month with the highest average low temperature is July (66°F).
The coldest month (with the lowest average low temperature) is January (21.4°F).
Average pressure in September
Rochester, IL
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Rochester, IL
- Average wind speed in September: 7mph
The windiest month (with the highest average wind speed) is January (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.2mph).
Average humidity in September
Rochester, IL
- Average humidity in September: 75%
The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).
Average rainfall in September
Rochester, IL
- Average rainfall in September: 1.89"
The wettest month (with the highest rainfall) is April (2.64").
The driest month (with the least rainfall) is December (1.14").
Average rainfall days in September
Rochester, IL
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is May (17.7 days).
The month with the least rainy days is February (6.2 days).
Average snowfall in September
Rochester, IL
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.85").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Rochester, IL
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.3 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
Rochester, IL
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 9h and 2min
The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in September
Rochester, IL
- Average sunshine days in September: 15.7 days
The month with the most sunshine days is October (18.7 days).
The month with the least sunshine days is July (11 days).
Average UV index in September
Rochester, IL
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Rochester, IL
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is June (Cloud cover 29).
Average visibility in September
Rochester, IL
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
Rochester, Illinois, USA
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