Illinois, United States Weather

  1. Illinois, United States Weather
  2. Current conditions
  3. Weather forecast
  4. Averages and extremes
  5. Yesterday's Data
  6. Temperature and possibility of rain in Illinois over the next 12 hours
  7. Temperature and possibility of rain in Illinois in the coming days
  8. Rainfall in Illinois in the coming days
  9. Illinois Weather Summary
  10. Weather averages by month
  11. Illinois's weather
  12. Frequently asked questions
  13. Comments
Illinois, Weather
(Photo by Anthony Fomin on Unsplash)

Current conditions

Updated:
19°C
66.2°F
°C °F

Condition: Overcast

Pressure: 986 hPa

Feel like: 20 °C

Temperature: 19°C

Cloud: 86%

Humidity: 68%

Wind: NW - 8 km/h

Visibility: 25.9 km

Weather forecast

Sun
21 Jun
15°C / 19°C
Violent Rain Showers
Mon
22 Jun
13°C / 22°C
Moderate Drizzle
Tue
23 Jun
11°C / 21°C
Overcast
Wed
24 Jun
13°C / 23°C
Drizzle
Thu
25 Jun
15°C / 24°C
Drizzle
Hourly forecast today:
02:00 AM
13° / 19°
13° / 19°
Overcast
68% 11 km/h
03:00 AM
15° / 19°
15° / 19°
Overcast
76% 20 km/h
04:00 AM
15° / 19°
15° / 19°
Overcast
79% 16 km/h
05:00 AM
15° / 18°
15° / 18°
Overcast
86% 10 km/h
06:00 AM
14° / 17°
14° / 17°
Overcast
86% 10 km/h
07:00 AM
15° / 17°
15° / 17°
Overcast
85% 14 km/h
08:00 AM
14° / 17°
14° / 17°
Overcast
83% 21 km/h
09:00 AM
15° / 17°
15° / 17°
Overcast
83% 20 km/h
10:00 AM
15° / 17°
15° / 17°
Mainly Clear
87% 12 km/h
11:00 AM
15° / 17°
15° / 17°
Overcast
89% 14 km/h
12:00 PM
15° / 17°
15° / 17°
Overcast
89% 26 km/h

30 Day Averages and Extremes

  • Average high 24.5°C
  • Average low 16.3°C
  • Hottest day 31°C (06 June 2026)
  • Coldest day 10°C (15 June 2026)
  • Average humidity 80.03%
  • Days with precipitation 25 days
  • Highest precipitation 58 mm (21 June 2026)

Yesterday's Data

  • Max: 25°C
  • Min: 14°C
  • Total Precipitation: 0 mm

Temperature and possibility of rain in Illinois over the next 12 hours

Temperature and possibility of rain in Illinois in the coming days

Rainfall in Illinois in the coming days

Illinois Climate Summary

Illinois features a Humid continental, no dry season, hot summer (Köppen classification: Dfa), with an average annual temperature of 12.07ºC (53.73ºF), which is about -0.57% lower than the national average for United States. Annually, the city experiences approximately 38.16 millimeters (1.5 inches) of rainfall, spread across 87.73 rainy days, accounting for 24.04% of the year.

Longitude 40.6331249
Latitude -89.3985283
Yearly high temperature 15.14ºC (59.25ºF)
Yearly low temperature 6.9ºC (44.42ºF)
Hottest month July 27.72ºC (81.9ºF)
Coldest month January -7.09ºC (19.24ºF)
Yearly precip 38.16mm (1.5in)
Days with rainfall 87.73 days (24.04%)
Driest month December (78.37%)
Wettest month May (77.38%)

Weather averages by month

Month High / Low (°C) Rain
January -1.0° / -7.09° 3.82 days
February 1.4° / -5.63° 4.73 days
March 9.03° / 1.17° 6.45 days
April 15.53° / 6.66° 9.0 days
May 22.0° / 13.0° 12.64 days
June 26.49° / 17.26° 10.55 days
July 27.72° / 18.69° 10.91 days
August 27.14° / 17.47° 7.73 days
September 24.45° / 14.28° 7.09 days
October 17.23° / 8.28° 6.36 days
November 8.89° / 1.57° 4.45 days
December 2.76° / -2.82° 4.0 days

Illinois's weather

Frequently asked questions

1. What is the hottest month in Illinois?

July has the highest average monthly temperature (daily mean of 27.72ºC) and January are the coolest (daily mean of -7.09ºC).

2. What should I wear in Illinois today?

For today's warm weather in Illinois, with temperatures between 21ºC to 24ºC (69.8ºF to 75.2ºF), you might consider wearing:
- Cotton or linen fabrics
- Sun hat or cap
- T-shirt or short-sleeve blouse
- Shorts or lightweight trousers

Temperature

Early
15°C / 19°C
Morning
15°C / 17°C
Afternoon
15°C / 21°C
Evening
11°C / 24°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 439
  • CO 191
  • NH3 0
  • NO2 10
  • O3 55
  • PM10 8
  • PM25 7
  • SO2 0
  • CH4 1,460

Sunrise / Sunset

10:26
01:31