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: Mainly Clear

Pressure: 987 hPa

Feel like: 19 °C

Temperature: 19°C

Cloud: 45%

Humidity: 73%

Wind: ESE - 9 km/h

Visibility: 20.8 km

Weather forecast

Fri
31 Jul
19°C / 25°C
Moderate Rain Showers
Sat
01 Aug
17°C / 21°C
Slight Rain Showers
Sun
02 Aug
14°C / 25°C
Mainly Clear
Mon
03 Aug
15°C / 26°C
Clear Sky
Tue
04 Aug
15°C / 26°C
Clear Sky
Hourly forecast today:
13:00 PM
14° / 19°
14° / 19°
Mainly Clear
73% 22 km/h
14:00 PM
15° / 22°
15° / 22°
Partly Cloudy
63% 18 km/h
15:00 PM
15° / 25°
15° / 25°
Clear Sky
53% 14 km/h
16:00 PM
15° / 26°
15° / 26°
Overcast
50% 11 km/h
17:00 PM
14° / 27°
14° / 27°
Partly Cloudy
45% 11 km/h
18:00 PM
13° / 28°
13° / 28°
Overcast
39% 9 km/h
19:00 PM
13° / 29°
13° / 29°
Overcast
37% 7 km/h
20:00 PM
12° / 30°
12° / 30°
Overcast
34% 8 km/h
21:00 PM
12° / 30°
12° / 30°
Overcast
33% 6 km/h
22:00 PM
11° / 30°
11° / 30°
Overcast
32% 9 km/h
23:00 PM
11° / 29°
11° / 29°
Overcast
32% 7 km/h

30 Day Averages and Extremes

  • Average high 27.73°C
  • Average low 18.2°C
  • Hottest day 34°C (27 July 2026)
  • Coldest day 11°C (23 July 2026)
  • Average humidity 77.7%
  • Days with precipitation 21 days
  • Highest precipitation 49 mm (01 August 2026)

Yesterday's Data

  • Max: 28°C
  • Min: 16°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:
- Lightweight, loose-fitting shorts
- Broad-brimmed sun hat
- High SPF sunscreen for outdoor activities
- UV-blocking sunglasses

Temperature

Early
13°C / 21°C
Morning
12°C / 16°C
Afternoon
15°C / 25°C
Evening
12°C / 30°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 415
  • CO 164
  • NH3 0
  • NO2 14
  • O3 33
  • PM10 7
  • PM25 6
  • SO2 3
  • CH4 1,400

Sunrise / Sunset

10:52
01:15