Fort Collins Air Quality in April
Across 2019–2025, Fort Collins's April air quality had a median AQI of 54 (Moderate) over 210 monitored days in the Fort Collins, CO area. 0.5% of April days (1 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 94.8% of days. The cleanest April on record here was 2022 (median AQI 50, 0 days above 100) and the worst was 2020 (median 49, 1 day above 100, peak AQI 115).
- Good: 41.4%
- Moderate: 58.1%
- Unhealthy for Sensitive Groups: 0.5%
- 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
As an Amazon Associate, we earn from qualifying purchases.
How is the air in Fort Collins in April?
Moderate on a typical day: median AQI 54 across 2019–2025, with 0.5% of April days above AQI 100. Ground-level ozone is the main driver.
- ✓41.4% of April days were Good (AQI 0–50), 58.1% Moderate (51–100).
- ✓1 day of 210 reached AQI 101+; the April peak was 115.
- ✓Best April: 2022; worst April: 2020.
Frequently asked questions
What is the air quality like in Fort Collins in April?▾
Across 2019–2025, the median daily AQI in Fort Collins in April was 54 (Moderate). 41.4% of days were Good, 58.1% Moderate, and 0.5% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is April a good time for outdoor exercise in Fort Collins?▾
A typical April day in Fort Collins is Moderate (median AQI 54): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of April days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Fort Collins's April air quality problems?▾
Ground-level ozone set the daily AQI on 94.8% of April days in Fort Collins. The highest April AQI recorded in 2019–2025 was 115 (Unhealthy for Sensitive Groups), in 2020.
Fort Collins April air quality, year by year
Fort Collins April air quality by year (Fort Collins, CO, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 30 | 53 | 0 | 80 | O3 |
| 2020worst | 30 | 49 | 1 | 115 | O3 |
| 2021 | 30 | 54 | 0 | 84 | O3 |
| 2022cleanest | 30 | 50 | 0 | 87 | O3 |
| 2023 | 30 | 63 | 0 | 90 | O3 |
| 2024 | 30 | 60 | 0 | 93 | O3 |
| 2025 | 30 | 55 | 0 | 100 | O3 |
What April air means in Fort Collins
A typical April day in Fort Collins is Moderate (median AQI 54): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of April days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
April's median AQI of 54 is in line with Fort Collins's whole-year median of 51, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median April AQI across every EPA metro area (100,677 metro-days, 2019–2025) is 44, so Fort Collins runs above the national April norm; 0.5% of its April days topped AQI 100 versus 0.7% nationally (about the same).
April is part of Fort Collins's spring season (March, April, May); the spring 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.