Metro area air quality · 2025

Ukiah, CA

Median AQI 38 (Good). 73.7% of monitored days rated Good across this metro's EPA monitoring network.

38
Median AQI
73.7%
Good-air days
0
Unhealthy days
53%
Cleaner than US metros

Ukiah, CA posted a 2025 median AQI of 38 (Good) with 73.7% Good days

According to the U.S. EPA Air Quality System, the Ukiah, CA CBSA recorded a median AQI of 38 across 365 monitored days in 2025, with 73.7% 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 Ukiah, CA CBSA's 73.7% Good-day share places it cleaner than 53% of US metros in 2025.
Closest median-AQI peer
Appleton, WI (72.3% Good, median AQI 38) is the closest nationwide median-AQI peer to Ukiah, CA.
2020–2025 Good-day shift
Ukiah, CA's Good-day share moved +5.7 points from 2020 to 2025 (median AQI -2).
Median AQI
Median AQI: 38

Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →

The verdict

Ukiah, CA's peak reading 81 stays in the lower max-AQI tercile on this extract. On the EPA scale the metro runs good, cleaner than the median US metro, with a median AQI of 38 and 73.7% of 365 monitored days in the Good band.

38
median AQI · Good
73.7%
days rated Good
53%
cleaner than US metros
81
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

2024 → 2025
  • Ukiah, CA metro's Good-day share rose from 66.7% to 73.7% between the 2024 and 2025 EPA annual releases, a change of +7.0 percentage points.
  • Ukiah, CA metro's median AQI fell from 43 to 38 between the 2024 and 2025 EPA annual releases, a change of -5 points.

Compared against 366 monitored days in 2024 and 365 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Ukiah, CA's peak reading 81 stays in the lower max-AQI tercile on this extract. Signature read: peak AQI 81 (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 38 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 269 Good (74%), 96 Moderate (26%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 59; the highest single-day reading hit 81 (Moderate).

Across 2020–2025, Good-day share shifted +5.7 points and median AQI moved -2 (improving). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Appleton, WI (72.3% good, AQI 38); Billings, MT (86.3% good, AQI 38); Burlington-South Burlington, VT (87.7% good, AQI 38).

Understanding AQI →

Air Quality Summary

Median AQI

38

Good

Good Days

73.7%

269 of 365 days

Max AQI

81

Moderate

Health Grade

Moderate

90th pct: 59

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

269

74%

Moderate

96

26%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Ukiah, CA metro area's air quality is rated Moderate based on 73.7% good air days. No unhealthy air days were recorded in 2025.

Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.

How does the Ukiah, CA metro compare?

How Ukiah, CA compares

Good-day share better than typical
Ukiah, CA 73.7%
Appleton, WI 72.3%
Typical US metro 70.6%
Median AQI better than typical
Ukiah, CA 38
Appleton, WI 38
Typical US metro 41
Unhealthy days / yr better than typical
Ukiah, CA 0
Appleton, WI 6
Typical US metro 1

5-Year Air Quality Trend

Air quality is improving in the Ukiah, CA metro. Highest Good-day share: 2025 (73.7%, 269 of 365 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 240 103 10 40
2021 210 147 2 46
2022 129 234 0 54
2023 144 216 0 53
2024 244 122 0 43
2025 269 96 0 38

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Ukiah, CA (38).

Appleton, WI

Median AQI 38 · 72.3% Good-day share

38

Billings, MT

Median AQI 38 · 86.3% Good-day share

38

Burlington-South Burlington, VT

Median AQI 38 · 87.7% Good-day share

38

Charlottesville, VA

Median AQI 38 · 81.0% Good-day share

38

Corning, NY

Median AQI 38 · 83.3% Good-day share

38

Dickinson, ND

Median AQI 38 · 82.7% Good-day share

38

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Ukiah, CA's 0 (independent of median AQI).

Aberdeen, SD

0 unhealthy-or-worse days · median AQI 27

27

Aberdeen, WA

0 unhealthy-or-worse days · median AQI 22

22

Adrian, MI

0 unhealthy-or-worse days · median AQI 41

41

Akron, OH

0 unhealthy-or-worse days · median AQI 45

45

Albany, GA

0 unhealthy-or-worse days · median AQI 46

46

Albany, OR

0 unhealthy-or-worse days · median AQI 27

27

Frequently Asked Questions

What is the 90th percentile AQI for Ukiah, CA? ▼
The 90th percentile AQI for the Ukiah, CA metro area is 59, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 81 (Moderate).
How many unhealthy air days does Ukiah, CA have? ▼
In 2025, the Ukiah, CA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 81.
What is the air quality in the Ukiah, CA metro area? ▼
The Ukiah, CA metro area has a median Air Quality Index (AQI) of 38, rated "Good." 73.7% of monitored days (269 out of 365) had good air quality in 2025.
Is air quality in Ukiah, CA getting better or worse? ▼
Air quality in the Ukiah, CA metro is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2025 at 73.7% (269 of 365 days). Lowest qualifying Good-day share: 2022 at 35.5% (129 of 363 days).
What does AQI 38 mean for health? ▼
An AQI of 38 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
How does Ukiah, CA compare to other metro areas? ▼
The Ukiah, CA metro has 73.7% good air days. Similar metros: Appleton, WI (72.3% good), Billings, MT (86.3% good), Burlington-South Burlington, VT (87.7% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Ukiah, 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, Ukiah, CA · 2020–2025