Visalia Air Quality in Fall

Across 2019–2025, Visalia's fall (September–November) air quality had a median AQI of 83 (Moderate) over 637 monitored days in the Visalia-Porterville, CA area. 33.9% of fall days (216 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 50.4% of days. The cleanest fall on record here was 2025 (median AQI 66, 6 days above 100) and the worst was 2020 (median 108, 51 days above 100, peak AQI 192).

83
Median AQI
Moderate
33.9%
Days above AQI 100
216 of 637 days
150
90th percentile AQI
worst 1 day in 10
961
Peak AQI
Hazardous
PM2.5
Main pollutant
50.4% of days
10.8%
Good days
69 of 637
  • Good: 10.8%
  • Moderate: 55.3%
  • Unhealthy for Sensitive Groups: 24.3%
  • Unhealthy or worse: 9.6%

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QUICK ANSWER

How is the air in Visalia in fall?

Moderate on a typical day: median AQI 83 across 2019–2025, with 33.9% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.

  • 10.8% of fall days were Good (AQI 0–50), 55.3% Moderate (51–100).
  • 216 days of 637 reached AQI 101+; the fall peak was 961.
  • Cleanest month: November; worst month: September.

Frequently asked questions

What is the air quality like in Visalia in fall?

Across 2019–2025, the median daily AQI in Visalia in fall was 83 (Moderate). 10.8% of days were Good, 55.3% Moderate, and 33.9% reached Unhealthy for Sensitive Groups or worse, based on 637 monitored days in EPA's Air Quality System.

Is fall a good time for outdoor exercise in Visalia?

A typical fall day in Visalia is Moderate (median AQI 83): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of fall days (33.9%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.

Which pollutant causes Visalia's fall air quality problems?

Fine particulate matter (PM2.5) set the daily AQI on 50.4% of fall days in Visalia. The highest fall AQI recorded in 2019–2025 was 961 (Hazardous), in 2020.

Visalia fall air quality, year by year

Visalia fall air quality by year (Visalia-Porterville, CA, EPA AQS daily AQI)

YearDays monitoredMedian AQIDays above 100Peak AQIMain pollutant
2019918425280O3
2020worst9110851192PM2.5
2021919744961PM2.5
2022919038182O3
2023917722242PM2.5
2024917730174O3
2025cleanest91666129PM2.5

What fall air means in Visalia

A typical fall day in Visalia is Moderate (median AQI 83): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of fall days (33.9%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.

Fall's median AQI of 83 is above Visalia's whole-year median of 71, making it one of the area's dirtier periods. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Visalia runs above the national Fall norm; 33.9% of its Fall days topped AQI 100 versus 1.5% nationally (above average).

Within the season, November is the cleanest month (median AQI 74, 13.8% of days above 100) and September the worst (median 107, 55.7% above 100).

Activity-specific thresholds: running, cycling, kids' sports.

Right now in Visalia

The latest EPA AirNow observation puts Visalia's AQI at 83 (PM10). The figures above are multi-year season statistics, not today's reading.

View current Visalia air quality →

Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Visalia-Porterville, 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.