Metro area air quality · 2025
Visalia-Porterville, CA
Median AQI 64 (Moderate). 24.1% of monitored days rated Good across this metro's EPA monitoring network.
- 64
- Median AQI
- 24.1%
- Good-air days
- 0
- Unhealthy days
- 1%
- Cleaner than US metros
Visalia-Porterville, CA posted a 2025 median AQI of 64 (Moderate) with 24.1% Good days
According to the U.S. EPA Air Quality System, the Visalia-Porterville, CA CBSA recorded a median AQI of 64 across 365 monitored days in 2025, with 24.1% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US metros
- The Visalia-Porterville, CA CBSA's 24.1% Good-day share places it cleaner than 1% of US metros in 2025.
- Closest median-AQI peer
- El Centro, CA (27.7% Good, median AQI 64) is the closest nationwide median-AQI peer to Visalia-Porterville, CA.
- 2020–2025 Good-day shift
- Visalia-Porterville, CA's Good-day share moved +7.4 points from 2020 to 2025 (median AQI -16).
- Median AQI
- Median AQI: 64
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
The Visalia-Porterville, CA metro runs moderate on the EPA scale, among the more polluted US metros, a median AQI of 64 with 24.1% of 365 monitored days in the Good band.
- 64
- median AQI · Moderate
- 24.1%
- days rated Good
- 1%
- cleaner than US metros
- 147
- worst single reading
No day crossed into the Unhealthy tier across the metro's monitors in 2025.
Annual release change
What changed in the 2025 EPA annual release
- Visalia-Porterville, CA metro's Unhealthy-category days fell from 28 to 0 between the 2024 and 2025 EPA annual releases, a change of -28 days.
- Visalia-Porterville, CA metro's peak single-day AQI fell from 185 to 147 between the 2024 and 2025 EPA annual releases, a change of -38 points.
- Visalia-Porterville, CA metro's median AQI fell from 71 to 64 between the 2024 and 2025 EPA annual releases, a change of -7 points.
Insights: Visalia-Porterville, CA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 64 over 365 measured days in 2025, which corresponds to a Moderate band and a Very Poor metro-wide health grade. The monitored-day split lands at 88 Good days (24%), 234 Moderate (64%), and 43 Unhealthy-for-Sensitive-Groups (12%). The 90th-percentile AQI finished at 105 while the highest single-day reading hit 147 (USG). Metro residents averaged roughly 7.2 clean-air days per 30-day window across the reporting year.
Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +7.4 points (measured against 261 monitored days in 2020 and 322 in 2025, so raw day counts are not comparable) and the median AQI moved -16 points, which classifies the multi-year trajectory as improving. The metro recorded no Unhealthy-tier days in this annual dataset. Metros with comparable AQI profiles include El Centro, CA (27.7% good, AQI 64); Houston-The Woodlands-Sugar Land, TX (10.1% good, AQI 63); Albuquerque, NM (24.9% good, AQI 61).
Air Quality Summary
Median AQI
64
Moderate
Good Days
24.1%
88 of 365 days
Max AQI
147
USG
Health Grade
Very Poor
90th pct: 105
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
88
24%
Moderate
234
64%
USG
43
12%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Visalia-Porterville, CA metro area's air quality is rated Very Poor based on 24.1% good air days. No unhealthy air days were recorded in 2025.
Air quality is acceptable most days, but 43 days reached "Unhealthy for Sensitive Groups". Sensitive groups should monitor real-time conditions at AirNow.gov.
How does the Visalia-Porterville, CA metro compare?
How Visalia-Porterville, CA compares
5-Year Air Quality Trend
Air quality is improving in the Visalia-Porterville, CA metro. Highest Good-day share: 2023 (31.1%, 94 of 302 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 52 | 179 | 30 | 80 | 225 |
| 2021 | 49 | 182 | 38 | 81 | 961 |
| 2022 | 58 | 193 | 8 | 77 | 182 |
| 2023 | 94 | 189 | 19 | 69 | 242 |
| 2024 | 76 | 179 | 28 | 71 | 185 |
| 2025 | 88 | 234 | 0 | 64 | 147 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Visalia-Porterville, CA (64).
El Centro, CA
Median AQI 64 · 27.7% Good-day share
Houston-The Woodlands-Sugar Land, TX
Median AQI 63 · 10.1% Good-day share
Albuquerque, NM
Median AQI 61 · 24.9% Good-day share
Fresno, CA
Median AQI 61 · 28.8% Good-day share
Las Cruces, NM
Median AQI 61 · 27.4% Good-day share
Las Vegas-Henderson-Paradise, NV
Median AQI 61 · 31.0% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Visalia-Porterville, CA's 0 (independent of median AQI).
Aberdeen, SD
0 unhealthy-or-worse days · median AQI 27
Aberdeen, WA
0 unhealthy-or-worse days · median AQI 22
Adrian, MI
0 unhealthy-or-worse days · median AQI 41
Akron, OH
0 unhealthy-or-worse days · median AQI 45
Albany, GA
0 unhealthy-or-worse days · median AQI 46
Albany, OR
0 unhealthy-or-worse days · median AQI 27
More Air Quality Data
Explore EPA air quality rankings and guides across U.S. metros and counties.
Cleanest Metro Areas
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Worst Air Quality
Counties and metros with the most unhealthy air days.
All Metro Areas
Annual AQI by CBSA for every monitored U.S. metro area.
Best and Worst City Air
What drives urban air quality and how metro areas compare.
Air Quality Guides
Frequently Asked Questions
What is the air quality in the Visalia-Porterville, CA metro area? ▼
How many unhealthy air days does Visalia-Porterville, CA have? ▼
Is air quality in Visalia-Porterville, CA getting better or worse? ▼
What does AQI 64 mean for health? ▼
What is the 90th percentile AQI for Visalia-Porterville, CA? ▼
How does Visalia-Porterville, CA compare to other metro areas? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. See our methodology for how AQI, median, and coverage figures are computed.
Read our methodology , how this data is sourced, computed, and verified.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary files (metro-level) · 2020–2025
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Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.