Fresno Air Quality in December
Across 2019–2025, Fresno's December air quality had a median AQI of 73 (Moderate) over 217 monitored days in the Fresno, CA area. 18.4% of December days (40 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 92.6% of days. The cleanest December on record here was 2025 (median AQI 73, 1 day above 100) and the worst was 2020 (median 91, 10 days above 100, peak AQI 126).
- Good: 17.5%
- Moderate: 64.1%
- Unhealthy for Sensitive Groups: 17.5%
- Unhealthy or worse: 0.9%
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How is the air in Fresno in December?
Moderate on a typical day: median AQI 73 across 2019–2025, with 18.4% of December days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓17.5% of December days were Good (AQI 0–50), 64.1% Moderate (51–100).
- ✓40 days of 217 reached AQI 101+; the December peak was 156.
- ✓Best December: 2025; worst December: 2020.
Frequently asked questions
What is the air quality like in Fresno in December?▾
Across 2019–2025, the median daily AQI in Fresno in December was 73 (Moderate). 17.5% of days were Good, 64.1% Moderate, and 18.4% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is December a good time for outdoor exercise in Fresno?▾
A typical December day in Fresno is Moderate (median AQI 73): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 5 of December days (18.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Fresno's December air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 92.6% of December days in Fresno. The highest December AQI recorded in 2019–2025 was 156 (Unhealthy), in 2020.
Fresno December air quality, year by year
Fresno December air quality by year (Fresno, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 60 | 2 | 112 | PM2.5 |
| 2020worst | 31 | 91 | 10 | 126 | PM2.5 |
| 2021 | 31 | 71 | 4 | 145 | PM2.5 |
| 2022 | 31 | 68 | 4 | 118 | PM2.5 |
| 2023 | 31 | 83 | 10 | 140 | PM2.5 |
| 2024 | 31 | 83 | 9 | 156 | PM2.5 |
| 2025cleanest | 31 | 73 | 1 | 101 | PM2.5 |
What December air means in Fresno
A typical December day in Fresno is Moderate (median AQI 73): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 5 of December days (18.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
December's median AQI of 73 is above Fresno's whole-year median of 67, making it one of the area's dirtier periods. Nationally, the median December AQI across every EPA metro area (95,590 metro-days, 2019–2025) is 39, so Fresno runs above the national December norm; 18.4% of its December days topped AQI 100 versus 0.7% nationally (above average).
December is part of Fresno's winter season (December, January, February); the winter page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Fresno
The latest EPA AirNow observation puts Fresno's AQI at 69 (PM10). The figures above are multi-year month statistics, not today's reading.
View current Fresno air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Fresno, CA), 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.