Burlington Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Burlington (Burlington-South Burlington, VT area) was June 25, 2023, when the daily AQI reached 160 (Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season. Across 2,557 monitored days in 2019–2025, 3 of the 10 worst days were Unhealthy (AQI 151+) or worse; 9 of the 10 were driven by fine particulate matter (PM2.5) and 1 by ground-level ozone, and 5 of them fell in 2023. The cleanest day was February 4, 2023 at AQI 0 (Good); the 10 best days span 3 different years.
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When were Burlington's worst and best air quality days?
Worst: June 25, 2023, AQI 160 (Unhealthy, PM2.5). Best: February 4, 2023, AQI 0 (Good). Based on 2,557 EPA-monitored days in the Burlington-South Burlington, VT area, 2019–2025.
- ✓3 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 104 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) drove 9 of the 10 worst days.
- ✓2023 accounts for 5 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Burlington?▾
June 25, 2023: the Burlington-South Burlington, VT area's daily AQI hit 160 (Unhealthy), driven by fine particulate matter (PM2.5), in wildfire smoke season. That is the highest of 2,557 monitored days in 2019–2025.
What was the best air quality day in Burlington?▾
February 4, 2023, with a daily AQI of 0 (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 Burlington's worst air quality day in 2025?▾
July 26, 2025, AQI 156 (Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season.
Which pollutant causes Burlington's worst air days?▾
Fine particulate matter (PM2.5) set the AQI on 9 of the 10 worst days; ground-level ozone on 1. The tables above list the defining pollutant for every day.
Burlington's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Burlington-South Burlington, VT 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) | 160 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 2 | (2025 page) | 156 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 3 | (2023 page) | 152 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 4 | (2023 page) | 135 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 5 | (2025 page) | 129 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 6 | (2021 page) | 129 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 7 | (2023 page) | 115 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 8 | (2025 page) | 108 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
| 9 | (2025 page) | 106 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 10 | (2023 page) | 104 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
Worst day of each year in Burlington
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 | 82 | Moderate | PM2.5 — fine particulate matter (PM2.5) | |
| 2020 | 98 | Moderate | PM2.5 — fine particulate matter (PM2.5) | |
| 2021 | 129 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2022 | 90 | Moderate | PM2.5 — fine particulate matter (PM2.5) | |
| 2023 | 160 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2024 | 84 | Moderate | O3 — ground-level ozone | |
| 2025 | 156 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
Burlington's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Burlington-South Burlington, VT area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2023 page) | 0 | Good | CO — carbon monoxide |
| 2 | (2023 page) | 0 | Good | CO — carbon monoxide |
| 3 | (2024 page) | 3 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2025 page) | 6 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 5 | (2024 page) | 6 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 6 | (2024 page) | 6 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 7 | (2024 page) | 7 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2025 page) | 8 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2024 page) | 8 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 10 | (2024 page) | 8 | Good | PM2.5 — fine particulate matter (PM2.5) |
Right now in Burlington
The latest EPA AirNow observation puts Burlington's AQI at 27 (PM2.5). The days above are historical records, not today's reading.
View current Burlington air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Burlington-South Burlington, VT), 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.