San Diego Air Quality in March
Across 2019–2025, San Diego's March air quality had a median AQI of 53 (Moderate) over 217 monitored days in the San Diego-Carlsbad, CA area. 0.5% of March days (1 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 49.3% of days. The cleanest March on record here was 2020 (median AQI 46, 0 days above 100) and the worst was 2019 (median 52, 1 day above 100, peak AQI 101).
- Good: 39.6%
- Moderate: 59.9%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.0%
Extra Protection for San Diego Homes
Air quality in San Diego is moderate (AQI 54), with fine particles (PM2.5) 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
As an Amazon Associate, we earn from qualifying purchases.
How is the air in San Diego in March?
Moderate on a typical day: median AQI 53 across 2019–2025, with 0.5% of March days above AQI 100. Ground-level ozone is the main driver.
- ✓39.6% of March days were Good (AQI 0–50), 59.9% Moderate (51–100).
- ✓1 day of 217 reached AQI 101+; the March peak was 101.
- ✓Best March: 2020; worst March: 2019.
Frequently asked questions
What is the air quality like in San Diego in March?▾
Across 2019–2025, the median daily AQI in San Diego in March was 53 (Moderate). 39.6% of days were Good, 59.9% Moderate, and 0.5% 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 San Diego?▾
A typical March day in San Diego is Moderate (median AQI 53): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of March 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 San Diego's March air quality problems?▾
Ground-level ozone set the daily AQI on 49.3% of March days in San Diego. The highest March AQI recorded in 2019–2025 was 101 (Unhealthy for Sensitive Groups), in 2019.
San Diego March air quality, year by year
San Diego March air quality by year (San Diego-Carlsbad, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 31 | 52 | 1 | 101 | PM2.5 |
| 2020cleanest | 31 | 46 | 0 | 72 | PM2.5 |
| 2021 | 31 | 51 | 0 | 77 | O3 |
| 2022 | 31 | 61 | 0 | 100 | O3 |
| 2023 | 31 | 53 | 0 | 77 | O3 |
| 2024 | 31 | 55 | 0 | 82 | PM2.5 |
| 2025 | 31 | 52 | 0 | 87 | PM2.5 |
What March air means in San Diego
A typical March day in San Diego is Moderate (median AQI 53): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of March days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
March's median AQI of 53 is below San Diego's whole-year median of 67, 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 San Diego runs above the national March norm; 0.5% of its March days topped AQI 100 versus 0.4% nationally (about the same).
March is part of San Diego's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in San Diego
The latest EPA AirNow observation puts San Diego's AQI at 54 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current San Diego air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (San Diego-Carlsbad, 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.