Madison Air Quality in Winter
Across 2019–2025, Madison's winter (December–February) air quality had a median AQI of 47 (Good) over 632 monitored days in the Madison, WI area. 0.0% of winter days (0 of 632) 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 38, 0 days above 100) and the worst was 2019 (median 52, 0 days above 100, peak AQI 88).
- Good: 55.7%
- Moderate: 44.3%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Improve Indoor Air Quality
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How is the air in Madison 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.
- ✓55.7% of winter days were Good (AQI 0–50), 44.3% Moderate (51–100).
- ✓0 days of 632 reached AQI 101+; the winter peak was 90.
- ✓Cleanest month: February; worst month: January.
Frequently asked questions
What is the air quality like in Madison in winter?▾
Across 2019–2025, the median daily AQI in Madison in winter was 47 (Good). 55.7% of days were Good, 44.3% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 632 monitored days in EPA's Air Quality System.
Is winter a good time for outdoor exercise in Madison?▾
A typical winter day in Madison 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 Madison's winter air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 100.0% of winter days in Madison. The highest winter AQI recorded in 2019–2025 was 90 (Moderate), in 2019.
Madison winter air quality, year by year
Madison winter air quality by year (Madison, WI, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 90 | 52 | 0 | 88 | PM2.5 |
| 2020 | 91 | 51 | 0 | 82 | PM2.5 |
| 2021 | 90 | 51 | 0 | 90 | PM2.5 |
| 2022 | 90 | 50 | 0 | 81 | PM2.5 |
| 2023 | 90 | 48 | 0 | 88 | PM2.5 |
| 2024 | 91 | 41 | 0 | 74 | PM2.5 |
| 2025cleanest | 90 | 38 | 0 | 71 | PM2.5 |
What winter air means in Madison
A typical winter day in Madison 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 Madison's whole-year median of 45, 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 Madison 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 46, 0.0% of days above 100) and January the worst (median 48, 0.0% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Madison
The latest EPA AirNow observation puts Madison's AQI at 49 (PM2.5). The figures above are multi-year season statistics, not today's reading.
View current Madison air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Madison, 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.