Chicago Air Quality in February
Across 2019–2025, Chicago's February air quality had a median AQI of 58 (Moderate) over 198 monitored days in the Chicago-Naperville-Elgin, IL-IN-WI area. 1.0% of February days (2 of 198) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 89.4% of days. The cleanest February on record here was 2023 (median AQI 54, 0 days above 100) and the worst was 2021 (median 66, 2 days above 100, peak AQI 104).
- Good: 21.2%
- Moderate: 77.8%
- Unhealthy for Sensitive Groups: 1.0%
- Unhealthy or worse: 0.0%
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How is the air in Chicago in February?
Moderate on a typical day: median AQI 58 across 2019–2025, with 1.0% of February days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓21.2% of February days were Good (AQI 0–50), 77.8% Moderate (51–100).
- ✓2 days of 198 reached AQI 101+; the February peak was 104.
- ✓Best February: 2023; worst February: 2021.
Frequently asked questions
What is the air quality like in Chicago in February?▾
Across 2019–2025, the median daily AQI in Chicago in February was 58 (Moderate). 21.2% of days were Good, 77.8% Moderate, and 1.0% reached Unhealthy for Sensitive Groups or worse, based on 198 monitored days in EPA's Air Quality System.
Is February a good time for outdoor exercise in Chicago?▾
A typical February day in Chicago is Moderate (median AQI 58): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 100 of February days (1.0%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Chicago's February air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 89.4% of February days in Chicago. The highest February AQI recorded in 2019–2025 was 104 (Unhealthy for Sensitive Groups), in 2021.
Chicago February air quality, year by year
Chicago February air quality by year (Chicago-Naperville-Elgin, IL-IN-WI, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 28 | 58 | 0 | 89 | PM2.5 |
| 2020 | 29 | 58 | 0 | 76 | PM2.5 |
| 2021worst | 28 | 66 | 2 | 104 | PM2.5 |
| 2022 | 28 | 59 | 0 | 88 | PM2.5 |
| 2023cleanest | 28 | 54 | 0 | 76 | PM2.5 |
| 2024 | 29 | 58 | 0 | 91 | PM2.5 |
| 2025 | 28 | 56 | 0 | 67 | PM2.5 |
What February air means in Chicago
A typical February day in Chicago is Moderate (median AQI 58): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 100 of February days (1.0%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
February's median AQI of 58 is in line with Chicago's whole-year median of 60, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median February AQI across every EPA metro area (87,428 metro-days, 2019–2025) is 41, so Chicago runs above the national February norm; 1.0% of its February days topped AQI 100 versus 0.4% nationally (about the same).
February is part of Chicago's winter season (December, January, February); the winter page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Chicago
The latest EPA AirNow observation puts Chicago's AQI at 46 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Chicago air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Chicago-Naperville-Elgin, IL-IN-WI), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.