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:
20°C
68.0°F
°C °F

Condition: Clear Sky

Pressure: 984 hPa

Feel like: 22 °C

Temperature: 20°C

Cloud: 0%

Humidity: 85%

Wind: SE - 9 km/h

Visibility: 15.8 km

Weather forecast

Wed
05 Aug
20°C / 28°C
Slight Thunderstorm
Thu
06 Aug
18°C / 27°C
Thunderstorm With Slight
Fri
07 Aug
19°C / 26°C
Violent Rain Showers
Sat
08 Aug
18°C / 30°C
Moderate Drizzle
Sun
09 Aug
23°C / 32°C
Drizzle
Hourly forecast today:
06:00 AM
18° / 20°
18° / 20°
Clear Sky
85% 21 km/h
07:00 AM
17° / 20°
17° / 20°
Mainly Clear
84% 22 km/h
08:00 AM
17° / 20°
17° / 20°
Partly Cloudy
85% 18 km/h
09:00 AM
17° / 19°
17° / 19°
Clear Sky
86% 15 km/h
10:00 AM
17° / 19°
17° / 19°
Clear Sky
88% 15 km/h
11:00 AM
16° / 18°
16° / 18°
Clear Sky
89% 19 km/h
12:00 PM
17° / 19°
17° / 19°
Clear Sky
90% 19 km/h
13:00 PM
18° / 21°
18° / 21°
Clear Sky
81% 24 km/h
14:00 PM
19° / 24°
19° / 24°
Clear Sky
74% 22 km/h
15:00 PM
19° / 26°
19° / 26°
Mainly Clear
66% 20 km/h
16:00 PM
18° / 27°
18° / 27°
Mainly Clear
60% 16 km/h

30 Day Averages and Extremes

  • Average high 27.3°C
  • Average low 17.93°C
  • Hottest day 35°C (18 August 2026)
  • Coldest day 11°C (23 July 2026)
  • Average humidity 78.47%
  • Days with precipitation 21 days
  • Highest precipitation 39 mm (01 August 2026)

Yesterday's Data

  • Max: 28°C
  • Min: 15°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
- Light, natural fabrics (like cotton or linen)
- Airy sandals or flip-flops
- Broad-brimmed sun hat

Temperature

Early
18°C / 22°C
Morning
17°C / 19°C
Afternoon
19°C / 26°C
Evening
15°C / 30°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 410
  • CO 169
  • NH3 0
  • NO2 16
  • O3 36
  • PM10 5
  • PM25 5
  • SO2 0
  • CH4 1,401

Sunrise / Sunset

10:57
01:09