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Illinois climate guide
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Below are average maximum temperatures at popular destinations in Illinois for next month - September. Select a destination to see the climate guide for all months of the year.
The climate guide for Illinois shows long term monthly weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.
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Metric (°C / mm) | Imperial (°F / inches)
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