Temperature in Illinois in July

Daytime highs, nighttime lows and the warmest cities in Illinois, the United States of America this July.

Illinois, the United States of America, a region in the United States of America, experiences maximum daytime temperatures in July ranging from 26°C (79°F) in Roscoe to 31°C (88°F) in O'Fallon. Nighttime temperatures generally drop to 20°C (68°F) in O'Fallon and 14°C (57°F) in Roscoe. The month of July is in the summer season. On average, July is the warmest month of the year in Illinois, the United States of America. So be prepared and pack summer clothes.

What is the temperature of the different cities in Illinois, the United States of America in July?

Discover the typical July temperatures for the most popular locations of Illinois on the map below. Detailed insights are just a click away.

Select a Month

Check the conditions for any month of the year.

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For a detailed overview over the year and the best time to visit Illinois, check out our Illinois's climate page.

See also: Illinois weather by month.

Best Places to Visit in Illinois in July

Click on a destination dot for more details. Toggle the map to compare temperatures or precipitation across Illinois.

Conditions Temperatures Precipitation
Avg daytime high -5°C (23°F) cold → 32°C (90°F) hot

Marker color shows the average daytime high temperature in July: blue is cold, red is hot.

See all July weather averages, cities and regions in Illinois

Illinois temperatures in July: frequently asked questions

How hot does it get in Illinois, the United States of America in July?

Average daytime highs in Illinois, the United States of America during July reach about 29°C (84°F) in Chicago.

How cold does it get at night in Illinois, the United States of America in July?

After dark, Chicago cools to about 19°C (66°F) on an average July night.

What is the warmest city in July in Illinois, the United States of America?

Data insights from our comprehensive database indicate that O'Fallon is the city with the highest warmth. Daytime peaks average near 31°C (88°F), while the nights are characterized by a low temperature close to 20°C (68°F).

What is the coldest city in July in Illinois, the United States of America?

The coldest city in July in Illinois, the United States of America is Roscoe when we check our database. The maximum daytime temperatures are around 26°C (79°F) and minimum nighttime temperatures fall around 14°C (57°F).

How much sun does Illinois, the United States of America get in July?

Chicago enjoys approximately 319 hours of sunshine, offering a mostly sunny climate that adds a pleasant and vibrant feel to the month.

Interested in more climate information?

We have much more information about the climate in Illinois.

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