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
Visalia-Porterville, CA lands in the lower Good-day tercile (24.1% Good), a thinner clean-air share than most CBSA peers here. On the EPA scale the metro runs moderate, among the more polluted US metros, with a median AQI of 64 and 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.
Visalia-Porterville, CA lands in the lower Good-day tercile (24.1% Good), a thinner clean-air share than most CBSA peers here. Signature read: 24.1% Good-day share (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 64 over 365 measured days in 2025 (Moderate / Very Poor). The monitored-day split lands at 88 Good (24%), 234 Moderate (64%), and 43 Unhealthy-for-Sensitive-Groups (12%). The 90th-percentile AQI finished at 105; the highest single-day reading hit 147 (USG).
Across 2020–2025, Good-day share shifted +7.4 points and median AQI moved -16 (improving). No Unhealthy-tier days appear 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
Frequently Asked Questions
How many unhealthy air days does Visalia-Porterville, CA have? ▼
What is the air quality in the Visalia-Porterville, CA metro area? ▼
Is air quality in Visalia-Porterville, CA getting better or worse? ▼
What does AQI 64 mean for health? ▼
How does Visalia-Porterville, CA compare to other metro areas? ▼
What is the 90th percentile AQI for Visalia-Porterville, CA? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Visalia-Porterville, CA, 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, Visalia-Porterville, CA · 2020–2025