Modesto Air Quality in 2025
In 2025, Modesto's air quality (Modesto, CA area) had a median daily AQI of 51 (Moderate) across 365 monitored days. 3 days (0.8%) reached Unhealthy for Sensitive Groups or worse, 182 were Good, and the year's peak AQI was 115 (Unhealthy for Sensitive Groups). Ground-level ozone set the daily AQI on 229 of those days. The cleanest month of 2025 was February (median AQI 38, 0 days above 100) and the worst was September (median 54, 1 day above 100, peak 108).
- Good: 49.9%
- Moderate: 49.3%
- Unhealthy for Sensitive Groups: 0.8%
- Unhealthy or worse: 0.0%
Extra Protection for Modesto Homes
Air quality in Modesto is moderate (AQI 63), with particle pollution the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
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How was Modesto's air quality in 2025?
Moderate on a typical day: median AQI 51, with 3 days above AQI 100 out of 365 monitored — the 1st cleanest of 7 years on record for the area.
- ✓Peak AQI in 2025: 115 (Unhealthy for Sensitive Groups).
- ✓Ground-level ozone was the main pollutant on 229 days.
- ✓Cleanest month: February; worst: September.
Frequently asked questions
What was the average AQI in Modesto in 2025?▾
EPA's Air Quality System puts Modesto's (Modesto, CA) median daily AQI for 2025 at 51, which is Moderate. 3 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 115.
Which month had the worst air quality in Modesto in 2025?▾
The cleanest month of 2025 was February (median AQI 38, 0 days above 100) and the worst was September (median 54, 1 day above 100, peak 108).
Was 2025 a good or bad year for Modesto's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2025 ranks 1st cleanest by days above AQI 100 — the best year on record here. 2025's median of 51 is below the area's typical annual median of 54.
Modesto month by month in 2025
Modesto air quality month by month, 2025 (Modesto, CA, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 65 | 0 | 87 | PM2.5 |
| Februarycleanest | 28 | 38 | 0 | 79 | O3 |
| March | 31 | 41 | 0 | 55 | O3 |
| April | 30 | 45 | 0 | 71 | O3 |
| May | 31 | 49 | 1 | 105 | O3 |
| June | 30 | 56 | 0 | 93 | O3 |
| July | 31 | 50 | 1 | 115 | O3 |
| August | 31 | 50 | 0 | 90 | O3 |
| Septemberworst | 30 | 54 | 1 | 108 | O3 |
| October | 31 | 43 | 0 | 85 | PM2.5 |
| November | 30 | 59 | 0 | 95 | PM2.5 |
| December | 31 | 65 | 0 | 98 | PM2.5 |
How 2025 compares
Among the 7 years EPA has published for the area (2019–2025), 2025 ranks 1st cleanest by days above AQI 100 — the best year on record here.
2025's median of 51 is below the area's typical annual median of 54.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Modesto
The latest EPA AirNow observation puts Modesto's AQI at 63 (PM10). The figures above are multi-year annual statistics, not today's reading.
View current Modesto air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Modesto, 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.