Metro area air quality · 2025

Olympia-Tumwater, WA

Median AQI 26 (Good). 98.1% of monitored days rated Good across this metro's EPA monitoring network.

26
Median AQI
98.1%
Good-air days
0
Unhealthy days
97%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 161 monitored days. EPA AQS →

The verdict

The Olympia-Tumwater, WA metro runs good on the EPA scale, among the cleanest 10% of US metros, a median AQI of 26 with 98.1% of 161 monitored days in the Good band.

26
median AQI · Good
98.1%
days rated Good
97%
cleaner than US metros
52
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2025.

Insights: Olympia-Tumwater, WA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 26 over 161 measured days in 2025, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 158 Good days (98%), 3 Moderate (2%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 44 while the highest single-day reading hit 52 (Moderate). Metro residents averaged roughly 29.4 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -158 and the median AQI moved -2 points, which classifies the multi-year trajectory as improving. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Branson, MO (100.0% good, AQI 26); Dodge City, KS (89.4% good, AQI 26); Moses Lake, WA (89.7% good, AQI 26).

Air Quality Summary

Median AQI

26

Good

Good Days

98.1%

158 of 161 days

Max AQI

52

Moderate

Health Grade

Excellent

90th pct: 44

AQI Day Breakdown (2025)

Distribution of 161 monitored days across EPA AQI categories.

Good

158

98%

Moderate

3

2%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Excellent

The Olympia-Tumwater, WA metro area's air quality is rated Excellent based on 98.1% 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 Olympia-Tumwater, WA metro compare?

How Olympia-Tumwater, WA compares

Good-day share better than US avg
Olympia-Tumwater, WA 98.1%
Branson, MO 100.0%
US average 71.3%
Median AQI better than US avg
Olympia-Tumwater, WA 26
Branson, MO 26
US average 41
Unhealthy days / yr better than US avg
Olympia-Tumwater, WA 0
Branson, MO 0
US average 1

5-Year Air Quality Trend

Air quality is improving in the Olympia-Tumwater, WA metro. Best year: 2024 (338 good days).

Year Good Moderate Unhealthy Median AQI
2020 316 43 3 28
2021 309 20 0 19
2022 309 36 2 28
2023 327 31 0 28
2024 338 24 0 26
2025 158 3 0 26

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Olympia-Tumwater, WA.

Branson, MO

AQI 26 · 100.0% good

26

Dodge City, KS

AQI 26 · 89.4% good

26

Moses Lake, WA

AQI 26 · 89.7% good

26

Port Angeles, WA

AQI 26 · 88.5% good

26

Aberdeen, SD

AQI 25 · 87.1% good

25

Anchorage, AK

AQI 25 · 78.6% good

25

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

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 Olympia-Tumwater, WA metro area? ▼
The Olympia-Tumwater, WA metro area has a median Air Quality Index (AQI) of 26, rated "Good." 98.1% of monitored days (158 out of 161) had good air quality in 2025.
How many unhealthy air days does Olympia-Tumwater, WA have? ▼
In 2025, the Olympia-Tumwater, WA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 52.
Is air quality in Olympia-Tumwater, WA getting better or worse? ▼
Air quality in the Olympia-Tumwater, WA metro is improving based on 5-year trends (2020-2025). Best year: 2024 with 338 good days. Worst year: 2025 with 158 good days.
What does AQI 26 mean for health? ▼
An AQI of 26 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Olympia-Tumwater, WA? ▼
The 90th percentile AQI for the Olympia-Tumwater, WA metro area is 44, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 52 (Moderate).
How does Olympia-Tumwater, WA compare to other metro areas? ▼
The Olympia-Tumwater, WA metro has 98.1% good air days. Similar metros: Branson, MO (100.0% good), Dodge City, KS (89.4% good), Moses Lake, WA (89.7% good).

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

Every figure on PlainAir 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.