Illinois, United States Weather
- Illinois, United States Weather
- Current conditions
- Weather forecast
- Averages and extremes
- Yesterday's Data
- 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 Weather Summary
- Weather averages by month
- Illinois's weather
- Frequently asked questions
- Comments
Current conditions
Condition: Overcast
Pressure: 982 hPa
Feel like: 30 °C
Temperature: 25°C
Cloud: 100%
Humidity: 84%
Wind: ESE - 4 km/h
Visibility: 15.6 km
30 Day Averages and Extremes
- Average high 23.0°C
- Average low 14.17°C
- Hottest day 32°C (05 September 2026)
- Coldest day 7°C (02 October 2026)
- Average humidity 77.0%
- Days with precipitation 21 days
- Highest precipitation 32 mm (16 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
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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:
- Breathable shorts or skirts
- Loose and airy fabrics like linen or cotton
- UV-protective sunglasses
- Lightweight t-shirt or tank top
Temperature
Air quality
Satisfactory air quality, minimal pollution, low risk
- CO2 461
- CO 135
- NH3 0
- NO2 5
- O3 93
- PM10 13
- PM25 12
- SO2 1
- CH4 1,363