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: Overcast

Pressure: 989 hPa

Feel like: 21 °C

Temperature: 22°C

Cloud: 100%

Humidity: 51%

Wind: NNW - 10 km/h

Visibility: 37.0 km

Weather forecast

Mon
14 Sep
15°C / 26°C
Slight Rain
Tue
15 Sep
19°C / 34°C
Moderate Drizzle
Wed
16 Sep
17°C / 22°C
Moderate Rain Showers
Thu
17 Sep
18°C / 26°C
Slight Rain Showers
Fri
18 Sep
15°C / 19°C
Slight Rain Showers
Hourly forecast today:
16:00 PM
12° / 22°
12° / 22°
Overcast
51% 11 km/h
17:00 PM
11° / 23°
11° / 23°
Overcast
49% 16 km/h
18:00 PM
10° / 23°
10° / 23°
Overcast
45% 23 km/h
19:00 PM
10° / 22°
10° / 22°
Overcast
44% 27 km/h
20:00 PM
8° / 22°
8° / 22°
Overcast
43% 18 km/h
21:00 PM
8° / 20°
8° / 20°
Overcast
46% 13 km/h
22:00 PM
9° / 21°
9° / 21°
Overcast
47% 21 km/h
23:00 PM
10° / 19°
10° / 19°
Overcast
55% 21 km/h
00:00 AM
10° / 18°
10° / 18°
Overcast
59% 31 km/h
01:00 AM
11° / 16°
11° / 16°
Overcast
73% 31 km/h
02:00 AM
13° / 15°
13° / 15°
Drizzle
89% 20 km/h

30 Day Averages and Extremes

  • Average high 27.43°C
  • Average low 16.5°C
  • Hottest day 34°C (01 September 2026)
  • Coldest day 8°C (20 September 2026)
  • Average humidity 69.77%
  • Days with precipitation 18 days
  • Highest precipitation 47 mm (16 September 2026)

Yesterday's Data

  • Max: 30°C
  • Min: 17°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 warm weather in Illinois, with temperatures between 20ºC to 23ºC (68.0ºF to 73.4ºF), you might consider wearing:
- Light, breathable socks
- Sunglasses
- Sun hat or cap
- T-shirt or short-sleeve blouse

Temperature

Early
20°C / 22°C
Morning
12°C / 18°C
Afternoon
11°C / 21°C
Evening
8°C / 20°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 433
  • CO 151
  • NH3 0
  • NO2 3
  • O3 64
  • PM10 2
  • PM25 2
  • SO2 0
  • CH4 1,385

Sunrise / Sunset

11:36
00:09