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:
1°C
33.8°F
°C °F

Condition: Clear Sky

Pressure: 990 hPa

Feel like: -2 °C

Temperature: 1°C

Cloud: 0%

Humidity: 81%

Wind: WSW - 11 km/h

Visibility: 18.4 km

Weather forecast

Mon
20 Apr
0°C / 14°C
Overcast
Tue
21 Apr
9°C / 21°C
Slight Rain Showers
Wed
22 Apr
14°C / 20°C
Drizzle
Thu
23 Apr
14°C / 24°C
Drizzle
Fri
24 Apr
12°C / 17°C
Slight Rain Showers
Hourly forecast today:
11:00 AM
-1° / 1°
-1° / 1°
Clear Sky
81% 20 km/h
12:00 PM
-1° / 1°
-1° / 1°
Clear Sky
81% 22 km/h
13:00 PM
0° / 4°
0° / 4°
Clear Sky
68% 36 km/h
14:00 PM
0° / 7°
0° / 7°
Clear Sky
57% 36 km/h
15:00 PM
0° / 8°
0° / 8°
Overcast
55% 34 km/h
16:00 PM
0° / 9°
0° / 9°
Overcast
52% 41 km/h
17:00 PM
-1° / 10°
-1° / 10°
Overcast
44% 35 km/h
18:00 PM
0° / 9°
0° / 9°
Overcast
48% 43 km/h
19:00 PM
-1° / 9°
-1° / 9°
Overcast
48% 40 km/h
20:00 PM
1° / 9°
1° / 9°
Overcast
57% 41 km/h
21:00 PM
0° / 8°
0° / 8°
Mainly Clear
51% 45 km/h

30 Day Averages and Extremes

  • Average high 18.43°C
  • Average low 8.77°C
  • Hottest day 28°C (17 April 2026)
  • Coldest day 0°C (07 April 2026)
  • Average humidity 69.83%
  • Days with precipitation 23 days
  • Highest precipitation 48 mm (24 April 2026)

Yesterday's Data

  • Max: 15°C
  • Min: 4°C
  • Total Precipitation: 12 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 cool weather in Illinois, with temperatures between 7ºC to 10ºC (44.6ºF to 50.0ºF), you should consider wearing:
- Light jacket or cardigan
- Thin gloves (optional for early mornings or late evenings)
- Casual shoes or sneakers
- Comfortable pants or jeans

Temperature

Early
-1°C / 5°C
Morning
-2°C / 2°C
Afternoon
0°C / 8°C
Evening
0°C / 8°C

Air quality

Good

Satisfactory air quality, minimal pollution, low risk

  • CO2 454
  • CO 162
  • NH3 0
  • NO2 4
  • O3 59
  • PM10 4
  • PM25 4
  • SO2 0
  • CH4 1,415

Sunrise / Sunset

11:12
00:40