Aurora, CO Air Quality in January
Across 2019–2025, Aurora's January air quality had a median AQI of 56 (Moderate) over 217 monitored days in the Denver-Aurora-Lakewood, CO area. 0.9% of January days (2 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 49.8% of days. The cleanest January on record here was 2025 (median AQI 52, 0 days above 100) and the worst was 2021 (median 58, 1 day above 100, peak AQI 109).
- Good: 28.1%
- Moderate: 71.0%
- Unhealthy for Sensitive Groups: 0.9%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Aurora
Today's main pollutant in Aurora is ground-level ozone (AQI 43). 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.
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How is the air in Aurora in January?
Moderate on a typical day: median AQI 56 across 2019–2025, with 0.9% of January days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓28.1% of January days were Good (AQI 0–50), 71.0% Moderate (51–100).
- ✓2 days of 217 reached AQI 101+; the January peak was 109.
- ✓Best January: 2025; worst January: 2021.
Frequently asked questions
What is the air quality like in Aurora in January?▾
Across 2019–2025, the median daily AQI in Aurora in January was 56 (Moderate). 28.1% of days were Good, 71.0% Moderate, and 0.9% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is January a good time for outdoor exercise in Aurora?▾
A typical January day in Aurora is Moderate (median AQI 56): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of January 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 Aurora's January air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 49.8% of January days in Aurora. The highest January AQI recorded in 2019–2025 was 109 (Unhealthy for Sensitive Groups), in 2021.
Aurora January air quality, year by year
Aurora January air quality by year (Denver-Aurora-Lakewood, CO, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 58 | 0 | 76 | PM2.5 |
| 2020 | 31 | 54 | 1 | 103 | NO2 |
| 2021worst | 31 | 58 | 1 | 109 | NO2 |
| 2022 | 31 | 57 | 0 | 77 | PM2.5 |
| 2023 | 31 | 58 | 0 | 89 | PM2.5 |
| 2024 | 31 | 55 | 0 | 82 | PM2.5 |
| 2025cleanest | 31 | 52 | 0 | 72 | PM2.5 |
What January air means in Aurora
A typical January day in Aurora is Moderate (median AQI 56): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of January days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
January's median AQI of 56 is below Aurora's whole-year median of 64, making it one of the area's cleaner periods. Nationally, the median January AQI across every EPA metro area (95,602 metro-days, 2019–2025) is 39, so Aurora runs above the national January norm; 0.9% of its January days topped AQI 100 versus 0.7% nationally (about the same).
January is part of Aurora's winter season (December, January, February); the winter page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Aurora
The latest EPA AirNow observation puts Aurora's AQI at 43 (O3). The figures above are multi-year month statistics, not today's reading.
View current Aurora air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Denver-Aurora-Lakewood, 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.