Modesto Air Quality in Spring
Across 2019–2025, Modesto's spring (March–May) air quality had a median AQI of 46 (Good) over 644 monitored days in the Modesto, CA area. 0.9% of spring days (6 of 644) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 64.6% of days. The cleanest spring on record here was 2019 (median AQI 44, 0 days above 100) and the worst was 2021 (median 52, 2 days above 100, peak AQI 115).
- Good: 64.6%
- Moderate: 34.5%
- Unhealthy for Sensitive Groups: 0.9%
- 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 spring?
Good on a typical day: median AQI 46 across 2019–2025, with 0.9% of spring days above AQI 100. Ground-level ozone is the main driver.
- ✓64.6% of spring days were Good (AQI 0–50), 34.5% Moderate (51–100).
- ✓6 days of 644 reached AQI 101+; the spring peak was 115.
- ✓Cleanest month: March; worst month: May.
Frequently asked questions
What is the air quality like in Modesto in spring?▾
Across 2019–2025, the median daily AQI in Modesto in spring was 46 (Good). 64.6% of days were Good, 34.5% Moderate, and 0.9% reached Unhealthy for Sensitive Groups or worse, based on 644 monitored days in EPA's Air Quality System.
Is spring a good time for outdoor exercise in Modesto?▾
A typical spring 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 spring days reached AQI 101+ in 2019–2025.
Which pollutant causes Modesto's spring air quality problems?▾
Ground-level ozone set the daily AQI on 64.6% of spring days in Modesto. The highest spring AQI recorded in 2019–2025 was 115 (Unhealthy for Sensitive Groups), in 2021.
Modesto spring air quality, year by year
Modesto spring air quality by year (Modesto, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 92 | 44 | 0 | 97 | O3 |
| 2020 | 92 | 41 | 1 | 105 | O3 |
| 2021worst | 92 | 52 | 2 | 115 | PM2.5 |
| 2022 | 92 | 53 | 1 | 114 | PM2.5 |
| 2023 | 92 | 44 | 1 | 108 | O3 |
| 2024 | 92 | 46 | 0 | 87 | O3 |
| 2025 | 92 | 45 | 1 | 105 | O3 |
What spring air means in Modesto
A typical spring 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 spring days reached AQI 101+ in 2019–2025.
Spring'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 Spring AQI across every EPA metro area (307,196 metro-days, 2019–2025) is 43, so Modesto runs in line with the national Spring norm; 0.9% of its Spring days topped AQI 100 versus 0.8% nationally (about the same).
Within the season, March is the cleanest month (median AQI 42, 0.0% of days above 100) and May the worst (median 49, 2.3% above 100).
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 season 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.