Modesto Air Quality in July
Across 2019–2025, Modesto's July air quality had a median AQI of 71 (Moderate) over 217 monitored days in the Modesto, CA area. 19.4% of July days (42 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 91.2% of days. The cleanest July on record here was 2025 (median AQI 50, 1 day above 100) and the worst was 2024 (median 93, 15 days above 100, peak AQI 147).
- Good: 24.4%
- Moderate: 56.2%
- Unhealthy for Sensitive Groups: 19.4%
- 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 July?
Moderate on a typical day: median AQI 71 across 2019–2025, with 19.4% of July days above AQI 100. Ground-level ozone is the main driver.
- ✓24.4% of July days were Good (AQI 0–50), 56.2% Moderate (51–100).
- ✓42 days of 217 reached AQI 101+; the July peak was 147.
- ✓Best July: 2025; worst July: 2024.
Frequently asked questions
What is the air quality like in Modesto in July?▾
Across 2019–2025, the median daily AQI in Modesto in July was 71 (Moderate). 24.4% of days were Good, 56.2% Moderate, and 19.4% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is July a good time for outdoor exercise in Modesto?▾
A typical July day in Modesto is Moderate (median AQI 71): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 5 of July days (19.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Modesto's July air quality problems?▾
Ground-level ozone set the daily AQI on 91.2% of July days in Modesto. The highest July AQI recorded in 2019–2025 was 147 (Unhealthy for Sensitive Groups), in 2024.
Modesto July air quality, year by year
Modesto July air quality by year (Modesto, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 51 | 5 | 143 | O3 |
| 2020 | 31 | 61 | 1 | 103 | O3 |
| 2021 | 31 | 90 | 9 | 143 | O3 |
| 2022 | 31 | 64 | 1 | 108 | O3 |
| 2023 | 31 | 84 | 10 | 122 | O3 |
| 2024worst | 31 | 93 | 15 | 147 | O3 |
| 2025cleanest | 31 | 50 | 1 | 115 | O3 |
What July air means in Modesto
A typical July day in Modesto is Moderate (median AQI 71): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 5 of July days (19.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
July's median AQI of 71 is above Modesto's whole-year median of 54, making it one of the area's dirtier periods. Nationally, the median July AQI across every EPA metro area (103,858 metro-days, 2019–2025) is 47, so Modesto runs above the national July norm; 19.4% of its July days topped AQI 100 versus 3.6% nationally (above average).
July is part of Modesto's summer season (June, July, August); the summer 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.