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:
14°C
57.2°F
°C °F

Condition: Overcast

Pressure: 994 hPa

Feel like: 13 °C

Temperature: 14°C

Cloud: 91%

Humidity: 80%

Wind: NE - 11 km/h

Visibility: 17.7 km

Weather forecast

Thu
24 Sep
12°C / 21°C
Overcast
Fri
25 Sep
15°C / 22°C
Drizzle
Sat
26 Sep
12°C / 16°C
Drizzle
Sun
27 Sep
12°C / 17°C
Moderate Drizzle
Mon
28 Sep
9°C / 22°C
Mainly Clear
Hourly forecast today:
09:00 AM
11° / 14°
11° / 14°
Overcast
80% 25 km/h
10:00 AM
10° / 13°
10° / 13°
Mainly Clear
84% 28 km/h
11:00 AM
11° / 13°
11° / 13°
Overcast
85% 28 km/h
12:00 PM
11° / 14°
11° / 14°
Overcast
83% 29 km/h
13:00 PM
11° / 14°
11° / 14°
Overcast
81% 30 km/h
14:00 PM
11° / 15°
11° / 15°
Overcast
80% 30 km/h
15:00 PM
11° / 16°
11° / 16°
Mainly Clear
76% 30 km/h
16:00 PM
12° / 17°
12° / 17°
Mainly Clear
73% 31 km/h
17:00 PM
13° / 17°
13° / 17°
Overcast
76% 29 km/h
18:00 PM
13° / 18°
13° / 18°
Mainly Clear
73% 31 km/h
19:00 PM
13° / 19°
13° / 19°
Overcast
70% 33 km/h

30 Day Averages and Extremes

  • Average high 22.03°C
  • Average low 12.87°C
  • Hottest day 32°C (15 September 2026)
  • Coldest day 3°C (05 October 2026)
  • Average humidity 74.27%
  • Days with precipitation 22 days
  • Highest precipitation 32 mm (16 September 2026)

Yesterday's Data

  • Max: 18°C
  • Min: 13°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 mild weather in Illinois, with temperatures between 16ºC to 19ºC (60.8ºF to 66.2ºF), consider wearing:
- Sun hat (if spending time outdoors)
- Comfortable jeans or slacks
- Casual sneakers or loafers
- Scarf (optional)

Temperature

Early
10°C / 13°C
Morning
11°C / 14°C
Afternoon
11°C / 16°C
Evening
13°C / 19°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 438
  • CO 162
  • NH3 0
  • NO2 9
  • O3 46
  • PM10 5
  • PM25 5
  • SO2 3
  • CH4 1,411

Sunrise / Sunset

11:46
23:52