Fresno Air Quality in May
Across 2019–2025, Fresno's May air quality had a median AQI of 57 (Moderate) over 217 monitored days in the Fresno, CA area. 11.1% of May days (24 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 89.4% of days. The cleanest May on record here was 2019 (median AQI 51, 2 days above 100) and the worst was 2025 (median 64, 5 days above 100, peak AQI 164).
- Good: 38.7%
- Moderate: 50.2%
- Unhealthy for Sensitive Groups: 10.6%
- Unhealthy or worse: 0.5%
Reduce Indoor Ozone in Fresno
Today's main pollutant in Fresno is ground-level ozone (AQI 93). 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.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How is the air in Fresno in May?
Moderate on a typical day: median AQI 57 across 2019–2025, with 11.1% of May days above AQI 100. Ground-level ozone is the main driver.
- ✓38.7% of May days were Good (AQI 0–50), 50.2% Moderate (51–100).
- ✓24 days of 217 reached AQI 101+; the May peak was 164.
- ✓Best May: 2019; worst May: 2025.
Frequently asked questions
What is the air quality like in Fresno in May?▾
Across 2019–2025, the median daily AQI in Fresno in May was 57 (Moderate). 38.7% of days were Good, 50.2% Moderate, and 11.1% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is May a good time for outdoor exercise in Fresno?▾
A typical May day in Fresno is Moderate (median AQI 57): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 9 of May days (11.1%) 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 May air quality problems?▾
Ground-level ozone set the daily AQI on 89.4% of May days in Fresno. The highest May AQI recorded in 2019–2025 was 164 (Unhealthy), in 2025.
Fresno May air quality, year by year
Fresno May air quality by year (Fresno, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 31 | 51 | 2 | 105 | O3 |
| 2020 | 31 | 54 | 5 | 143 | O3 |
| 2021 | 31 | 56 | 4 | 126 | O3 |
| 2022 | 31 | 54 | 3 | 122 | O3 |
| 2023 | 31 | 54 | 3 | 126 | O3 |
| 2024 | 31 | 64 | 2 | 108 | O3 |
| 2025worst | 31 | 64 | 5 | 164 | O3 |
What May air means in Fresno
A typical May day in Fresno is Moderate (median AQI 57): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 9 of May days (11.1%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
May's median AQI of 57 is below Fresno's whole-year median of 67, making it one of the area's cleaner periods. Nationally, the median May AQI across every EPA metro area (104,064 metro-days, 2019–2025) is 44, so Fresno runs above the national May norm; 11.1% of its May days topped AQI 100 versus 1.3% nationally (above average).
May is part of Fresno's spring season (March, April, May); the spring 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 93 (O3). 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.