Cheyenne Air Quality in Winter
Across 2019–2025, Cheyenne's winter (December–February) air quality had a median AQI of 39 (Good) over 632 monitored days in the Cheyenne, WY area. 0.0% of winter days (0 of 632) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 86.4% of days. The cleanest winter on record here was 2020 (median AQI 37, 0 days above 100) and the worst was 2024 (median 42, 0 days above 100, peak AQI 58).
- Good: 95.1%
- Moderate: 4.9%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Cheyenne
Today's main pollutant in Cheyenne is ground-level ozone (AQI 31). 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 Cheyenne in winter?
Good on a typical day: median AQI 39 across 2019–2025, with 0.0% of winter days above AQI 100. Ground-level ozone is the main driver.
- ✓95.1% of winter days were Good (AQI 0–50), 4.9% Moderate (51–100).
- ✓0 days of 632 reached AQI 101+; the winter peak was 77.
- ✓Cleanest month: January; worst month: February.
Frequently asked questions
What is the air quality like in Cheyenne in winter?▾
Across 2019–2025, the median daily AQI in Cheyenne in winter was 39 (Good). 95.1% of days were Good, 4.9% 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 Cheyenne?▾
A typical winter day in Cheyenne sits in the Good range (median AQI 39), 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 Cheyenne's winter air quality problems?▾
Ground-level ozone set the daily AQI on 86.4% of winter days in Cheyenne. The highest winter AQI recorded in 2019–2025 was 77 (Moderate), in 2024.
Cheyenne winter air quality, year by year
Cheyenne winter air quality by year (Cheyenne, WY, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 90 | 38 | 0 | 62 | O3 |
| 2020cleanest | 91 | 37 | 0 | 52 | O3 |
| 2021 | 90 | 39 | 0 | 77 | O3 |
| 2022 | 90 | 39 | 0 | 52 | O3 |
| 2023 | 90 | 40 | 0 | 60 | O3 |
| 2024worst | 91 | 42 | 0 | 58 | O3 |
| 2025 | 90 | 41 | 0 | 60 | O3 |
What winter air means in Cheyenne
A typical winter day in Cheyenne sits in the Good range (median AQI 39), 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 39 is below Cheyenne's whole-year median of 44, making it one of the area's cleaner periods. Nationally, the median Winter AQI across every EPA metro area (278,620 metro-days, 2019–2025) is 40, so Cheyenne runs in line with the national Winter norm; 0.0% of its Winter days topped AQI 100 versus 0.6% nationally (about the same).
Within the season, January is the cleanest month (median AQI 38, 0.0% of days above 100) and February the worst (median 41, 0.0% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Cheyenne
The latest EPA AirNow observation puts Cheyenne's AQI at 31 (O3). The figures above are multi-year season statistics, not today's reading.
View current Cheyenne air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Cheyenne, WY), 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.