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:
22°C
71.6°F
°C °F

Condition: Fog

Pressure: 987 hPa

Feel like: 24 °C

Temperature: 22°C

Cloud: 100%

Humidity: 99%

Wind: ESE - 17 km/h

Visibility: 0.1 km

Weather forecast

Sun
20 Sep
16°C / 24°C
Drizzle
Mon
21 Sep
13°C / 16°C
Moderate Drizzle
Tue
22 Sep
11°C / 14°C
Drizzle
Wed
23 Sep
10°C / 20°C
Overcast
Thu
24 Sep
10°C / 19°C
Overcast
Hourly forecast today:
03:00 AM
22° / 22°
22° / 22°
Fog
99% 32 km/h
04:00 AM
20° / 21°
20° / 21°
Mainly Clear
92% 33 km/h
05:00 AM
20° / 21°
20° / 21°
Mainly Clear
93% 31 km/h
06:00 AM
20° / 20°
20° / 20°
Clear Sky
95% 32 km/h
07:00 AM
19° / 20°
19° / 20°
Clear Sky
95% 24 km/h
08:00 AM
19° / 20°
19° / 20°
Clear Sky
95% 28 km/h
09:00 AM
19° / 20°
19° / 20°
Clear Sky
95% 30 km/h
10:00 AM
19° / 20°
19° / 20°
Clear Sky
94% 32 km/h
11:00 AM
19° / 21°
19° / 21°
Clear Sky
93% 25 km/h
12:00 PM
19° / 21°
19° / 21°
Overcast
93% 21 km/h
13:00 PM
20° / 22°
20° / 22°
Overcast
93% 16 km/h

30 Day Averages and Extremes

  • Average high 23.5°C
  • Average low 14.73°C
  • Hottest day 34°C (04 September 2026)
  • Coldest day 6°C (02 October 2026)
  • Average humidity 77.1%
  • Days with precipitation 19 days
  • Highest precipitation 45 mm (20 September 2026)

Yesterday's Data

  • Max: 23°C
  • Min: 20°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 26ºC (78.8ºF), consider wearing:
- Open-toed sandals or light sneakers
- Wide-brimmed sun hat
- UV-protective sunglasses
- Thin, moisture-wicking socks

Temperature

Early
22°C / 22°C
Morning
19°C / 20°C
Afternoon
21°C / 22°C
Evening
22°C / 26°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 450
  • CO 173
  • NH3 0
  • NO2 7
  • O3 55
  • PM10 4
  • PM25 3
  • SO2 1
  • CH4 1,384

Sunrise / Sunset

11:42
23:59