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: Drizzle

Pressure: 985 hPa

Feel like: 21 °C

Temperature: 20°C

Cloud: 100%

Humidity: 94%

Wind: SSW - 15 km/h

Visibility: 12.6 km

Weather forecast

Fri
26 Jun
17°C / 19°C
Drizzle Dense Intensity
Sat
27 Jun
15°C / 24°C
Thunderstorm With Slight
Sun
28 Jun
20°C / 30°C
Thunderstorm With Slight
Mon
29 Jun
22°C / 31°C
Slight Thunderstorm
Tue
30 Jun
22°C / 32°C
Slight Thunderstorm
Hourly forecast today:
03:00 AM
19° / 20°
19° / 20°
Drizzle
94% 26 km/h
04:00 AM
19° / 20°
19° / 20°
Partly Cloudy
94% 19 km/h
05:00 AM
19° / 20°
19° / 20°
Overcast
96% 23 km/h
06:00 AM
19° / 19°
19° / 19°
Partly Cloudy
96% 11 km/h
07:00 AM
18° / 19°
18° / 19°
Clear Sky
95% 14 km/h
08:00 AM
17° / 18°
17° / 18°
Mainly Clear
93% 18 km/h
09:00 AM
18° / 19°
18° / 19°
Overcast
96% 16 km/h
10:00 AM
17° / 18°
17° / 18°
Overcast
94% 12 km/h
11:00 AM
17° / 18°
17° / 18°
Overcast
96% 14 km/h
12:00 PM
18° / 19°
18° / 19°
Overcast
94% 15 km/h
13:00 PM
18° / 21°
18° / 21°
Overcast
85% 14 km/h

30 Day Averages and Extremes

  • Average high 26.17°C
  • Average low 17.4°C
  • Hottest day 33°C (01 July 2026)
  • Coldest day 10°C (15 June 2026)
  • Average humidity 77.47%
  • Days with precipitation 23 days
  • Highest precipitation 45 mm (26 June 2026)

Yesterday's Data

  • Max: 24°C
  • Min: 15°C
  • Total Precipitation: 1 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 26ºC (78.8ºF), consider wearing:
- Lightweight t-shirt or tank top
- Wide-brimmed sun hat
- Thin, moisture-wicking socks
- Breathable shorts or skirts

Temperature

Early
19°C / 20°C
Morning
18°C / 19°C
Afternoon
17°C / 24°C
Evening
13°C / 25°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 435
  • CO 148
  • NH3 0
  • NO2 8
  • O3 60
  • PM10 5
  • PM25 4
  • SO2 0
  • CH4 1,392

Sunrise / Sunset

10:28
01:32