Visalia Air Quality in October

Across 2019–2025, Visalia's October air quality had a median AQI of 80 (Moderate) over 217 monitored days in the Visalia-Porterville, CA area. 32.2% of October days (70 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 45.6% of days. The cleanest October on record here was 2025 (median AQI 64, 0 days above 100) and the worst was 2020 (median 112, 17 days above 100, peak AQI 181).

80
Median AQI
Moderate
32.2%
Days above AQI 100
70 of 217 days
149
90th percentile AQI
worst 1 day in 10
280
Peak AQI
Very Unhealthy
O3
Main pollutant
45.6% of days
10.1%
Good days
22 of 217
  • Good: 10.1%
  • Moderate: 57.6%
  • Unhealthy for Sensitive Groups: 22.1%
  • Unhealthy or worse: 10.1%

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QUICK ANSWER

How is the air in Visalia in October?

Moderate on a typical day: median AQI 80 across 2019–2025, with 32.2% of October days above AQI 100. Ground-level ozone is the main driver.

  • 10.1% of October days were Good (AQI 0–50), 57.6% Moderate (51–100).
  • 70 days of 217 reached AQI 101+; the October peak was 280.
  • Best October: 2025; worst October: 2020.

Frequently asked questions

What is the air quality like in Visalia in October?

Across 2019–2025, the median daily AQI in Visalia in October was 80 (Moderate). 10.1% of days were Good, 57.6% Moderate, and 32.2% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.

Is October a good time for outdoor exercise in Visalia?

A typical October day in Visalia is Moderate (median AQI 80): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of October days (32.2%) 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 October air quality problems?

Ground-level ozone set the daily AQI on 45.6% of October days in Visalia. The highest October AQI recorded in 2019–2025 was 280 (Very Unhealthy), in 2020.

Visalia October air quality, year by year

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

YearDays monitoredMedian AQIDays above 100Peak AQIMain pollutant
201931806280O3
2020worst3111217181O3
20213111116205PM2.5
20223110015147O3
202331605126PM2.5
2024318711174O3
2025cleanest3164093PM2.5

What October air means in Visalia

A typical October day in Visalia is Moderate (median AQI 80): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of October days (32.2%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.

October's median AQI of 80 is above Visalia's whole-year median of 71, making it one of the area's dirtier periods. Nationally, the median October AQI across every EPA metro area (102,872 metro-days, 2019–2025) is 38, so Visalia runs above the national October norm; 32.2% of its October days topped AQI 100 versus 1.3% nationally (above average).

October is part of Visalia's fall season (September, October, November); the fall page pools all three months.

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 month 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.