Rockford Air Quality in Winter
Across 2019–2025, Rockford's winter (December–February) air quality had a median AQI of 47 (Good) over 601 monitored days in the Rockford, IL area. 0.0% of winter days (0 of 601) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 100.0% of days. The cleanest winter on record here was 2025 (median AQI 33, 0 days above 100) and the worst was 2019 (median 55, 0 days above 100, peak AQI 83).
- Good: 54.7%
- Moderate: 45.3%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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How is the air in Rockford in winter?
Good on a typical day: median AQI 47 across 2019–2025, with 0.0% of winter days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓54.7% of winter days were Good (AQI 0–50), 45.3% Moderate (51–100).
- ✓0 days of 601 reached AQI 101+; the winter peak was 95.
- ✓Cleanest month: February; worst month: December.
Frequently asked questions
What is the air quality like in Rockford in winter?▾
Across 2019–2025, the median daily AQI in Rockford in winter was 47 (Good). 54.7% of days were Good, 45.3% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 601 monitored days in EPA's Air Quality System.
Is winter a good time for outdoor exercise in Rockford?▾
A typical winter day in Rockford sits in the Good range (median AQI 47), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of winter days reached AQI 101+ in 2019–2025.
Which pollutant causes Rockford's winter air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 100.0% of winter days in Rockford. The highest winter AQI recorded in 2019–2025 was 95 (Moderate), in 2019.
Rockford winter air quality, year by year
Rockford winter air quality by year (Rockford, IL, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 79 | 55 | 0 | 83 | PM2.5 |
| 2020 | 91 | 47 | 0 | 87 | PM2.5 |
| 2021 | 85 | 53 | 0 | 95 | PM2.5 |
| 2022 | 90 | 49 | 0 | 87 | PM2.5 |
| 2023 | 90 | 47 | 0 | 77 | PM2.5 |
| 2024 | 86 | 43 | 0 | 74 | PM2.5 |
| 2025cleanest | 80 | 33 | 0 | 66 | PM2.5 |
What winter air means in Rockford
A typical winter day in Rockford sits in the Good range (median AQI 47), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of winter days reached AQI 101+ in 2019–2025.
Winter's median AQI of 47 is in line with Rockford's whole-year median of 47, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Winter AQI across every EPA metro area (278,620 metro-days, 2019–2025) is 40, so Rockford runs above the national Winter norm; 0.0% of its Winter days topped AQI 100 versus 0.6% nationally (about the same).
Within the season, February is the cleanest month (median AQI 45, 0.0% of days above 100) and December the worst (median 48, 0.0% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Rockford
The latest EPA AirNow observation puts Rockford's AQI at 22 (PM2.5). The figures above are multi-year season statistics, not today's reading.
View current Rockford air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Rockford, IL), 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.