Modesto Air Quality in April
Across 2019–2025, Modesto's April air quality had a median AQI of 46 (Good) over 210 monitored days in the Modesto, CA area. 0.5% of April days (1 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 66.2% of days. The cleanest April on record here was 2020 (median AQI 41, 0 days above 100) and the worst was 2023 (median 45, 1 day above 100, peak AQI 108).
- Good: 66.7%
- Moderate: 32.9%
- Unhealthy for Sensitive Groups: 0.5%
- 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 is the air in Modesto in April?
Good on a typical day: median AQI 46 across 2019–2025, with 0.5% of April days above AQI 100. Ground-level ozone is the main driver.
- ✓66.7% of April days were Good (AQI 0–50), 32.9% Moderate (51–100).
- ✓1 day of 210 reached AQI 101+; the April peak was 108.
- ✓Best April: 2020; worst April: 2023.
Frequently asked questions
What is the air quality like in Modesto in April?▾
Across 2019–2025, the median daily AQI in Modesto in April was 46 (Good). 66.7% of days were Good, 32.9% Moderate, and 0.5% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is April a good time for outdoor exercise in Modesto?▾
A typical April day in Modesto sits in the Good range (median AQI 46), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of April days reached AQI 101+ in 2019–2025.
Which pollutant causes Modesto's April air quality problems?▾
Ground-level ozone set the daily AQI on 66.2% of April days in Modesto. The highest April AQI recorded in 2019–2025 was 108 (Unhealthy for Sensitive Groups), in 2023.
Modesto April air quality, year by year
Modesto April air quality by year (Modesto, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 30 | 44 | 0 | 97 | O3 |
| 2020cleanest | 30 | 41 | 0 | 51 | O3 |
| 2021 | 30 | 55 | 0 | 90 | PM2.5 |
| 2022 | 30 | 51 | 0 | 97 | PM2.5 |
| 2023worst | 30 | 45 | 1 | 108 | O3 |
| 2024 | 30 | 46 | 0 | 71 | O3 |
| 2025 | 30 | 45 | 0 | 71 | O3 |
What April air means in Modesto
A typical April day in Modesto sits in the Good range (median AQI 46), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of April days reached AQI 101+ in 2019–2025.
April's median AQI of 46 is below Modesto's whole-year median of 54, making it one of the area's cleaner periods. Nationally, the median April AQI across every EPA metro area (100,677 metro-days, 2019–2025) is 44, so Modesto runs in line with the national April norm; 0.5% of its April days topped AQI 100 versus 0.7% nationally (about the same).
April 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.