Modesto Air Quality in March
Across 2019–2025, Modesto's March air quality had a median AQI of 42 (Good) over 217 monitored days in the Modesto, CA area. 0.0% of March days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 53.9% of days. The cleanest March on record here was 2020 (median AQI 36, 0 days above 100) and the worst was 2022 (median 52, 0 days above 100, peak AQI 65).
- Good: 72.4%
- Moderate: 27.6%
- Unhealthy for Sensitive Groups: 0.0%
- 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.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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How is the air in Modesto in March?
Good on a typical day: median AQI 42 across 2019–2025, with 0.0% of March days above AQI 100. Ground-level ozone is the main driver.
- ✓72.4% of March days were Good (AQI 0–50), 27.6% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the March peak was 69.
- ✓Best March: 2020; worst March: 2022.
Frequently asked questions
What is the air quality like in Modesto in March?▾
Across 2019–2025, the median daily AQI in Modesto in March was 42 (Good). 72.4% of days were Good, 27.6% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is March a good time for outdoor exercise in Modesto?▾
A typical March day in Modesto sits in the Good range (median AQI 42), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of March days reached AQI 101+ in 2019–2025.
Which pollutant causes Modesto's March air quality problems?▾
Ground-level ozone set the daily AQI on 53.9% of March days in Modesto. The highest March AQI recorded in 2019–2025 was 69 (Moderate), in 2022.
Modesto March air quality, year by year
Modesto March air quality by year (Modesto, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 40 | 0 | 68 | O3 |
| 2020cleanest | 31 | 36 | 0 | 68 | O3 |
| 2021 | 31 | 51 | 0 | 69 | PM2.5 |
| 2022worst | 31 | 52 | 0 | 65 | PM2.5 |
| 2023 | 31 | 42 | 0 | 56 | O3 |
| 2024 | 31 | 39 | 0 | 54 | O3 |
| 2025 | 31 | 41 | 0 | 55 | O3 |
What March air means in Modesto
A typical March day in Modesto sits in the Good range (median AQI 42), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of March days reached AQI 101+ in 2019–2025.
March's median AQI of 42 is below Modesto's whole-year median of 54, making it one of the area's cleaner periods. Nationally, the median March AQI across every EPA metro area (102,455 metro-days, 2019–2025) is 42, so Modesto runs in line with the national March norm; 0.0% of its March days topped AQI 100 versus 0.4% nationally (about the same).
March is part of Modesto's spring season (March, April, May); the spring page pools all three months.
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 month 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.