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:
18°C
64.4°F
°C °F

Condition: Clear Sky

Pressure: 988 hPa

Feel like: 19 °C

Temperature: 18°C

Cloud: 5%

Humidity: 93%

Wind: SSE - 5 km/h

Visibility: 12.2 km

Weather forecast

Sat
08 Aug
20°C / 28°C
Overcast
Sun
09 Aug
20°C / 31°C
Slight Thunderstorm
Mon
10 Aug
21°C / 32°C
Overcast
Tue
11 Aug
20°C / 29°C
Thunderstorm With Slight
Wed
12 Aug
18°C / 30°C
Moderate Drizzle
Hourly forecast today:
09:00 AM
17° / 18°
17° / 18°
Clear Sky
93% 12 km/h
10:00 AM
16° / 18°
16° / 18°
Clear Sky
93% 6 km/h
11:00 AM
16° / 17°
16° / 17°
Mainly Clear
94% 7 km/h
12:00 PM
18° / 18°
18° / 18°
Mainly Clear
98% 8 km/h
13:00 PM
19° / 20°
19° / 20°
Overcast
96% 8 km/h
14:00 PM
19° / 20°
19° / 20°
Overcast
96% 8 km/h
15:00 PM
20° / 22°
20° / 22°
Overcast
91% 11 km/h
16:00 PM
21° / 23°
21° / 23°
Overcast
87% 11 km/h
17:00 PM
22° / 26°
22° / 26°
Partly Cloudy
79% 8 km/h
18:00 PM
22° / 27°
22° / 27°
Mainly Clear
73% 12 km/h
19:00 PM
22° / 28°
22° / 28°
Mainly Clear
69% 12 km/h

30 Day Averages and Extremes

  • Average high 26.13°C
  • Average low 16.67°C
  • Hottest day 34°C (27 July 2026)
  • Coldest day 10°C (14 August 2026)
  • Average humidity 78.87%
  • Days with precipitation 22 days
  • Highest precipitation 39 mm (01 August 2026)

Yesterday's Data

  • Max: 26°C
  • Min: 19°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 very hot weather in Illinois, with the high temperatures above 30ºC (86.0ºF), consider wearing:
- Ultra-thin, breathable socks
- Airy sandals or flip-flops
- Sleeveless tops or vests
- Lightweight, loose-fitting shorts

Temperature

Early
19°C / 20°C
Morning
17°C / 18°C
Afternoon
20°C / 22°C
Evening
19°C / 30°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 438
  • CO 145
  • NH3 0
  • NO2 6
  • O3 57
  • PM10 3
  • PM25 2
  • SO2 0
  • CH4 1,378

Sunrise / Sunset

11:00
01:06