Rockford Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Rockford (Rockford, IL area) was June 28, 2023, when the daily AQI reached 242 (Very Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season. Across 2,511 monitored days in 2019–2025, 4 of the 10 worst days were Unhealthy (AQI 151+) or worse; 6 of the 10 were driven by fine particulate matter (PM2.5) and 4 by ground-level ozone, and 8 of them fell in 2023. The cleanest day was November 22, 2024 at AQI 11 (Good); the 10 best days span 3 different years.
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When were Rockford's worst and best air quality days?
Worst: June 28, 2023, AQI 242 (Very Unhealthy, PM2.5). Best: November 22, 2024, AQI 11 (Good). Based on 2,511 EPA-monitored days in the Rockford, IL area, 2019–2025.
- ✓4 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 119 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) drove 6 of the 10 worst days.
- ✓2023 accounts for 8 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Rockford?▾
June 28, 2023: the Rockford, IL area's daily AQI hit 242 (Very Unhealthy), driven by fine particulate matter (PM2.5), in wildfire smoke season. That is the highest of 2,511 monitored days in 2019–2025.
What was the best air quality day in Rockford?▾
November 22, 2024, with a daily AQI of 11 (Good). The daily AQI is the highest reading from any monitor in the area, so even the cleanest day reflects the area's worst monitor.
What was Rockford's worst air quality day in 2025?▾
July 31, 2025, AQI 169 (Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season.
Which pollutant causes Rockford's worst air days?▾
Fine particulate matter (PM2.5) set the AQI on 6 of the 10 worst days; ground-level ozone on 4. The tables above list the defining pollutant for every day.
Rockford's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Rockford, IL area (EPA AQS). The daily AQI is the highest reading from any monitor in the area that day.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2023 page) | 242 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 2 | (2023 page) | 215 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 3 | (2023 page) | 191 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 4 | (2025 page) | 169 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 5 | (2023 page) | 133 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 6 | (2023 page) | 133 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 7 | (2023 page) | 133 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
| 8 | (2023 page) | 123 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 9 | (2023 page) | 120 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 10 | (2024 page) | 119 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
Worst day of each year in Rockford
The single highest-AQI day in each year on record. Click a year for its full month-by-month statistics.
| Year | Worst day | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 2019 | 102 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2020 | 101 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season | |
| 2021 | 100 | Moderate | O3 — ground-level ozone, in peak ozone season | |
| 2022 | 97 | Moderate | O3 — ground-level ozone, in peak ozone season | |
| 2023 | 242 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2024 | 119 | Unhealthy for Sensitive Groups | O3 — ground-level ozone | |
| 2025 | 169 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
Rockford's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Rockford, IL area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2024 page) | 11 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 2 | (2025 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 3 | (2024 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2025 page) | 13 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 5 | (2024 page) | 13 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 6 | (2025 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 7 | (2025 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2024 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2024 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 10 | (2021 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
Right now in Rockford
The latest EPA AirNow observation puts Rockford's AQI at 22 (PM2.5). The days above are historical records, 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.