Fort Collins Air Quality in November
Across 2019–2025, Fort Collins's November air quality had a median AQI of 45 (Good) over 210 monitored days in the Fort Collins, CO area. 0.0% of November days (0 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 68.6% of days. The cleanest November on record here was 2019 (median AQI 44, 0 days above 100) and the worst was 2024 (median 47, 0 days above 100, peak AQI 64).
- Good: 76.7%
- Moderate: 23.3%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Fort Collins
Today's main pollutant in Fort Collins is ground-level ozone (AQI 36). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How is the air in Fort Collins in November?
Good on a typical day: median AQI 45 across 2019–2025, with 0.0% of November days above AQI 100. Ground-level ozone is the main driver.
- ✓76.7% of November days were Good (AQI 0–50), 23.3% Moderate (51–100).
- ✓0 days of 210 reached AQI 101+; the November peak was 75.
- ✓Best November: 2019; worst November: 2024.
Frequently asked questions
What is the air quality like in Fort Collins in November?▾
Across 2019–2025, the median daily AQI in Fort Collins in November was 45 (Good). 76.7% of days were Good, 23.3% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is November a good time for outdoor exercise in Fort Collins?▾
A typical November day in Fort Collins sits in the Good range (median AQI 45), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of November days reached AQI 101+ in 2019–2025.
Which pollutant causes Fort Collins's November air quality problems?▾
Ground-level ozone set the daily AQI on 68.6% of November days in Fort Collins. The highest November AQI recorded in 2019–2025 was 75 (Moderate), in 2024.
Fort Collins November air quality, year by year
Fort Collins November air quality by year (Fort Collins, CO, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 30 | 44 | 0 | 54 | O3 |
| 2020 | 30 | 45 | 0 | 59 | O3 |
| 2021 | 30 | 46 | 0 | 75 | O3 |
| 2022 | 30 | 45 | 0 | 59 | O3 |
| 2023 | 30 | 47 | 0 | 56 | O3 |
| 2024worst | 30 | 47 | 0 | 64 | O3 |
| 2025 | 30 | 46 | 0 | 67 | O3 |
What November air means in Fort Collins
A typical November day in Fort Collins sits in the Good range (median AQI 45), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of November days reached AQI 101+ in 2019–2025.
November's median AQI of 45 is below Fort Collins's whole-year median of 51, making it one of the area's cleaner periods. Nationally, the median November AQI across every EPA metro area (92,704 metro-days, 2019–2025) is 39, so Fort Collins runs above the national November norm; 0.0% of its November days topped AQI 100 versus 0.6% nationally (about the same).
November is part of Fort Collins's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Fort Collins
The latest EPA AirNow observation puts Fort Collins's AQI at 36 (O3). The figures above are multi-year month statistics, not today's reading.
View current Fort Collins air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Fort Collins, CO), 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.