Illinois weather in September
Thinking about venturing to Illinois this September and curious about the weather conditions to expect? This page holds all the key information you seek, responding to your question:
What is the weather like in Illinois in September?
Illinois is a region in the United States of America. September in Illinois generally has temperatures that range from pleasant to warm, with precipitation levels ranging from moderate to high.
During the day temperatures vary from pleasant in Roscoe at 21°C to warm in Metropolis at 28°C. At night it cools down to 15°C in Metropolis and 9°C in Roscoe.
In September, precipitation varies across different areas. From moderate rainfall in Freeport with an average of 70 mm to high rainfall in Roscoe with 124 mm. Meanwhile, Chicago enjoys approximately 226 hours of sunshine, offering a mostly sunny climate that adds a pleasant and vibrant feel to the month.
To learn more about the conditions in specific areas of Illinois in September, check out the map below. For more details on the yearly weather, visit our Illinois climate page.
Where to go in Illinois in September
perfect weather
pleasant
tolerable
unpleasant
poor
Popular destinations in Illinois
What is the weather like in September for the 5 most popular destinations in Illinois?
Average weather in Chicago
In September Chicago generally has high temperatures with maximum daytime temperatures around 24°C, minimum nighttime temperatures around 14°C and moderate monthly rainfall. So on average the conditions are perfect that month.
Max temperature
Max temp
Min temperature
Min temp
Monthly sun hours
Sun hours
Monthly rainfall
Rainfall
Monthly rainy days
Rainy days
Weather conditions
Weather
Average weather in Schaumburg
In September Schaumburg generally has high temperatures with maximum daytime temperatures around 24°C, minimum nighttime temperatures around 12°C and high monthly rainfall. So on average the conditions are pleasant that month.
Max temperature
Max temp
Min temperature
Min temp
Monthly sun hours
Sun hours
Monthly rainfall
Rainfall
Monthly rainy days
Rainy days
Weather conditions
Weather
Average weather in Rosemont
In September Rosemont generally has high temperatures with maximum daytime temperatures around 24°C, minimum nighttime temperatures around 14°C and moderate monthly rainfall. So on average the conditions are perfect that month.
Max temperature
Max temp
Min temperature
Min temp
Monthly sun hours
Sun hours
Monthly rainfall
Rainfall
Monthly rainy days
Rainy days
Weather conditions
Weather
Average weather in Joliet
In September Joliet generally has high temperatures with maximum daytime temperatures around 25°C, minimum nighttime temperatures around 13°C and moderate monthly rainfall. So on average the conditions are perfect that month.
Max temperature
Max temp
Min temperature
Min temp
Monthly sun hours
Sun hours
Monthly rainfall
Rainfall
Monthly rainy days
Rainy days
Weather conditions
Weather
Average weather in Naperville
In September Naperville generally has high temperatures with maximum daytime temperatures around 25°C, minimum nighttime temperatures around 12°C and moderate monthly rainfall. So on average the conditions are perfect that month.
Max temperature
Max temp
Min temperature
Min temp
Monthly sun hours
Sun hours
Monthly rainfall
Rainfall
Monthly rainy days
Rainy days
Weather conditions
Weather
Is your destination not in the list? Have a look at other destinations in Illinois, in the United States of America.
Is September the best time to visit Illinois?
We consider September to be one of the best times to travel to Illinois. Typically, the climate in Chicago is perfect. However, the weather conditions may vary depending on your destination.
Generally speaking, September provides perfect weather in Chicago. On the other hand, the weather in January, February, March, November and December tend to be poor.
Interested in more climate information?
We have much more information about the climate in Illinois.
Interested in the weather conditions in a specific month? Select the month below.
Weather and climate has detailed information for every country in the world. Are you going to the United States of America? Get detailed historical weather averages for many cities in the United States of America.
Not sure yet where to go? We now have a tool which recommends destinations that suit your ideal climate conditions. Find out where to go with our weather planner.