Chicago · United States · 1995–2024 averages
Chicago weather, month by month. September is the pick.
Thirty years of averages for Chicago, United States — how hot it really feels, when the rain arrives, and what the air is like. September comes out on top; March is the one to skip.
The year at a glance
Tap a month for its full breakdown.
September
bestscore 82/100Mild, sticky and some rain, with moderate air.
- Feels like
- 22°
- mild
- Real temp
- 22°
- mild
- Humidity
- 71%
- sticky
- Rain
- 78mm
- some rain
- Cloud cover
- 47%
- bright
- Air quality
- 51
- moderate
- Daylight
- 12.5h
- even
Month by month, metric by metric
Each strip covers the same twelve months, so you can see where the rain lands and how the air shifts with it.
Feels like
peaks at 29° in July
Real temp
-1–27° in the shade across the year
Humidity
71% at its driest, 76% at its most oppressive
Rain
113mm in May, 56mm in February
Cloud cover
47% at its clearest, 72% at its greyest
Air quality
worst in June, cleanest in October
Daylight
9.2h to 15.2h of daylight across the year
Chicago's air changes sharply through the year
The air is at its worst in June at 71 AQI (moderate), and at its cleanest in October at 44 (clean). It tracks the seasons closely.
Every month in full
All twelve months, all seven measures.
| Month | Feels like | Real temp | Humidity | Rain | Cloud cover | Air quality | Daylight |
|---|---|---|---|---|---|---|---|
| January | -6° freezing | -1° freezing | 76% sweaty | 60mm dryish | 72% grey | 50 clean | 9.5h short |
| February | -4° freezing | 1° freezing | 75% sweaty | 56mm dryish | 65% mixed | 54 moderate | 10.6h shortish |
| March | 1° freezing | 5° cold | 75% sweaty | 69mm dryish | 64% mixed | 53 moderate | 12h even |
| April | 8° cold | 11° cold | 73% sticky | 100mm some rain | 63% mixed | 52 moderate | 13.4h even |
| May | 17° cool | 18° cool | 75% sweaty | 113mm some rain | 62% mixed | 61 moderate | 14.6h long days |
| June | 25° mild | 24° mild | 73% sticky | 98mm some rain | 56% mixed | 71 moderate | 15.2h long days |
| July | 29° warm | 27° mild | 72% sticky | 100mm some rain | 49% bright | 66 moderate | 14.9h long days |
| August | 28° warm | 26° mild | 73% sticky | 100mm some rain | 50% bright | 59 moderate | 13.8h even |
| September | 22° mild | 22° mild | 71% sticky | 78mm some rain | 47% bright | 51 moderate | 12.5h even |
| October | 13° cold | 16° cool | 71% sticky | 91mm some rain | 56% mixed | 44 clean | 11.1h shortish |
| November | 4° freezing | 8° cold | 72% sticky | 61mm dryish | 63% mixed | 44 clean | 9.8h short |
| December | -2° freezing | 2° freezing | 75% sweaty | 60mm dryish | 71% grey | 46 clean | 9.2h short |
Chicago weather questions
- What is the best time to visit Chicago?
- September scores best across temperature, rain, humidity and air quality — 22° feels-like, 78mm of rain and 71% humidity. March is the month to avoid: 69mm of rain and 53 AQI.
- How hot does Chicago get?
- July is the peak, at 29° feels-like (27° in the shade) — warm. Even in September it reaches 22°.
- When is the rainy season in Chicago?
- May is the wettest month at 113mm, and February the driest at just 56mm.
- Is air quality a problem in Chicago?
- June is the worst month at 71 AQI (moderate), and October the best at 44 (clean).
Weather normals from Open-Meteo (ERA5 reanalysis, 1995–2024) and CAMS air quality (2015–2024), licensed CC-BY-4.0. Contains modified Copernicus Climate Change Service information. These are long-run averages, not forecasts — any given year will differ.
Going in September? You won't be the only one.
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