Illinois Climate (Weather Averages)

The Illinois Climate Guide is perfect for planning your holiday. Monthly weather averages give the best indication of what the weather is usually like for every month of the year including figures for temperature, rainfall and sunshine.

Illinois Weather Illinois Summary Illinois Climate Illinois Today Illinois Forecast Illinois When Best
Illinois Weather Illinois Summary Illinois Climate Illinois Today Illinois Forecast Illinois When Best
J F M A M J J A S O N D
Max Daytime Temperature (°C) -1°C (30°F) Max Daytime Temperature in January in Illinois (Chicago) 2°C (36°F) Max Daytime Temperature in February in Illinois (Chicago) 7°C (45°F) Max Daytime Temperature in March in Illinois (Chicago) 15°C (59°F) Max Daytime Temperature in April in Illinois (Chicago) 21°C (70°F) Max Daytime Temperature in May in Illinois (Chicago) 27°C (81°F) Max Daytime Temperature in June in Illinois (Chicago) 29°C (84°F) Max Daytime Temperature in July in Illinois (Chicago) 28°C (82°F) Max Daytime Temperature in August in Illinois (Chicago) 24°C (75°F) Max Daytime Temperature in September in Illinois (Chicago) 18°C (64°F) Max Daytime Temperature in October in Illinois (Chicago) 9°C (48°F) Max Daytime Temperature in November in Illinois (Chicago) 2°C (36°F) Max Daytime Temperature in December in Illinois (Chicago)
Min Night-time Temperature (°C) -9°C (16°F) Min Night-time Temperature in January in Illinois (Chicago) -7°C (19°F) Min Night-time Temperature in February in Illinois (Chicago) -1°C (30°F) Min Night-time Temperature in March in Illinois (Chicago) 4°C (39°F) Min Night-time Temperature in April in Illinois (Chicago) 10°C (50°F) Min Night-time Temperature in May in Illinois (Chicago) 15°C (59°F) Min Night-time Temperature in June in Illinois (Chicago) 18°C (64°F) Min Night-time Temperature in July in Illinois (Chicago) 18°C (64°F) Min Night-time Temperature in August in Illinois (Chicago) 13°C (55°F) Min Night-time Temperature in September in Illinois (Chicago) 7°C (45°F) Min Night-time Temperature in October in Illinois (Chicago) 1°C (34°F) Min Night-time Temperature in November in Illinois (Chicago) -6°C (21°F) Min Night-time Temperature in December in Illinois (Chicago)
Hours of Sunshine (Daily) 4 Hours of Bright Sunshine per day (45% of Daylight Hours) in January in Illinois (Chicago) 5 Hours of Bright Sunshine per day (46% of Daylight Hours) in February in Illinois (Chicago) 6 Hours of Bright Sunshine per day (50% of Daylight Hours) in March in Illinois (Chicago) 7 Hours of Bright Sunshine per day (55% of Daylight Hours) in April in Illinois (Chicago) 9 Hours of Bright Sunshine per day (62% of Daylight Hours) in May in Illinois (Chicago) 10 Hours of Bright Sunshine per day (68% of Daylight Hours) in June in Illinois (Chicago) 10 Hours of Bright Sunshine per day (69% of Daylight Hours) in July in Illinois (Chicago) 9 Hours of Bright Sunshine per day (67% of Daylight Hours) in August in Illinois (Chicago) 8 Hours of Bright Sunshine per day (61% of Daylight Hours) in September in Illinois (Chicago) 6 Hours of Bright Sunshine per day (56% of Daylight Hours) in October in Illinois (Chicago) 4 Hours of Bright Sunshine per day (39% of Daylight Hours) in November in Illinois (Chicago) 3 Hours of Bright Sunshine per day (37% of Daylight Hours) in December in Illinois (Chicago)
Hours of Daylight (Daily) 10 Hours of Daylight in January in Illinois (Chicago) 11 Hours of Daylight in February in Illinois (Chicago) 12 Hours of Daylight in March in Illinois (Chicago) 13 Hours of Daylight in April in Illinois (Chicago) 15 Hours of Daylight in May in Illinois (Chicago) 15 Hours of Daylight in June in Illinois (Chicago) 15 Hours of Daylight in July in Illinois (Chicago) 14 Hours of Daylight in August in Illinois (Chicago) 12 Hours of Daylight in September in Illinois (Chicago) 11 Hours of Daylight in October in Illinois (Chicago) 10 Hours of Daylight in November in Illinois (Chicago) 9 Hours of Daylight in December in Illinois (Chicago)
Heat and Humidity Discomfort No Heat & Humidity in January in Illinois (Chicago) No Heat & Humidity in February in Illinois (Chicago) No Heat & Humidity in March in Illinois (Chicago) No Heat & Humidity in April in Illinois (Chicago) No Heat & Humidity in May in Illinois (Chicago) Low Heat & Humidity in June in Illinois (Chicago) Moderate Heat & Humidity in July in Illinois (Chicago) Moderate Heat & Humidity in August in Illinois (Chicago) No Heat & Humidity in September in Illinois (Chicago) No Heat & Humidity in October in Illinois (Chicago) No Heat & Humidity in November in Illinois (Chicago) No Heat & Humidity in December in Illinois (Chicago)
Days with some Rainfall 12 Days with some Rainfall in January in Illinois (Chicago) 10 Days with some Rainfall in February in Illinois (Chicago) 13 Days with some Rainfall in March in Illinois (Chicago) 13 Days with some Rainfall in April in Illinois (Chicago) 11 Days with some Rainfall in May in Illinois (Chicago) 10 Days with some Rainfall in June in Illinois (Chicago) 10 Days with some Rainfall in July in Illinois (Chicago) 9 Days with some Rainfall in August in Illinois (Chicago) 9 Days with some Rainfall in September in Illinois (Chicago) 9 Days with some Rainfall in October in Illinois (Chicago) 11 Days with some Rainfall in November in Illinois (Chicago) 12 Days with some Rainfall in December in Illinois (Chicago)
Monthly Rainfall (mm) 44 mm (1.7 inches) Monthly Rainfall in January in Illinois (Chicago) 38 mm (1.5 inches) Monthly Rainfall in February in Illinois (Chicago) 69 mm (2.7 inches) Monthly Rainfall in March in Illinois (Chicago) 96 mm (3.8 inches) Monthly Rainfall in April in Illinois (Chicago) 87 mm (3.4 inches) Monthly Rainfall in May in Illinois (Chicago) 98 mm (3.9 inches) Monthly Rainfall in June in Illinois (Chicago) 100 mm (3.9 inches) Monthly Rainfall in July in Illinois (Chicago) 100 mm (3.9 inches) Monthly Rainfall in August in Illinois (Chicago) 90 mm (3.5 inches) Monthly Rainfall in September in Illinois (Chicago) 64 mm (2.5 inches) Monthly Rainfall in October in Illinois (Chicago) 74 mm (2.9 inches) Monthly Rainfall in November in Illinois (Chicago) 66 mm (2.6 inches) Monthly Rainfall in December in Illinois (Chicago)
UV Index (Maximum) UV (Maximum) Index 1 (Low) in January in Illinois (Chicago) UV (Maximum) Index 2 (Low) in February in Illinois (Chicago) UV (Maximum) Index 4 (Moderate) in March in Illinois (Chicago) UV (Maximum) Index 6 (High) in April in Illinois (Chicago) UV (Maximum) Index 7 (High) in May in Illinois (Chicago) UV (Maximum) Index 9 (Very High) in June in Illinois (Chicago) UV (Maximum) Index 9 (Very High) in July in Illinois (Chicago) UV (Maximum) Index 8 (Very High) in August in Illinois (Chicago) UV (Maximum) Index 6 (High) in September in Illinois (Chicago) UV (Maximum) Index 4 (Moderate) in October in Illinois (Chicago) UV (Maximum) Index 2 (Low) in November in Illinois (Chicago) UV (Maximum) Index 1 (Low) in December in Illinois (Chicago)
Sea Temperature (°C) 4°C (39°F) Sea Temperature in January in Illinois (Chicago) 3°C (37°F) Sea Temperature in February in Illinois (Chicago) 3°C (37°F) Sea Temperature in March in Illinois (Chicago) 3°C (37°F) Sea Temperature in April in Illinois (Chicago) 6°C (43°F) Sea Temperature in May in Illinois (Chicago) 12°C (54°F) Sea Temperature in June in Illinois (Chicago) 19°C (66°F) Sea Temperature in July in Illinois (Chicago) 21°C (70°F) Sea Temperature in August in Illinois (Chicago) 19°C (66°F) Sea Temperature in September in Illinois (Chicago) 14°C (57°F) Sea Temperature in October in Illinois (Chicago) 9°C (48°F) Sea Temperature in November in Illinois (Chicago) 5°C (41°F) Sea Temperature in December in Illinois (Chicago)
J F M A M J J A S O N D
 		    
 
Illinois Holidays Illinois Flights Illinois Hotels Illinois Hire Cars Illinois Villas Illinois Transfers
Illinois Holidays Illinois Flights Illinois Hotels Illinois Hire Cars Illinois Villas Illinois Transfers

The Illinois Climate Guide shown above is based on the Chicago Climate Guide. Please note that the weather may vary across this region. Below is a list of all the destinations in Illinois with available Climate Guides.

  Champaign   Chicago   Decatur   Galena   Marion   Springfield  

Illinois Weather by Month
Check the weather for a particular month in Illinois by selecting a month from the list below. Alternatively check which month usually has the Best Weather in Illinois. If you are not sure where to go, why not try our Holiday Planner.
  · January
  · February
  · March
   · April
  · May
  · June
   · July
  · August
  · September
   · October
  · November
  · December
Popular Climate Guide Regions

1.

Cyprus

2.

Tenerife, Canary Islands, Spain

3.

Tunisia

4.

Sharm el-Sheikh, Egypt

5.

Mauritius

6.

Crete, Greece

7.

Dalaman and Marmaris Coast, Turkey

8.

Cape Verde

9.

Rhodes, Greece

10.

Antalya Coast, Turkey
Popular Climate Guide Destinations

1.

Santa Cruz de Tenerife, Tenerife, Canary Islands, Spain

2.

Nicosia, Cyprus

3.

Sharm el Sheikh Airport, Sharm el-Sheikh, Egypt

4.

Tunis, Tunisia

5.

Port Louis, Mauritius

6.

Khania, Crete, Greece

7.

Dalaman, Dalaman and Marmaris Coast, Turkey

8.

Praia, Santiago, Cape Verde

9.

Rhodes Town, Rhodes, Greece

10.

Antalya, Antalya Coast, Turkey
 		    
 
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