Metro area air quality · 2025

Olympia-Tumwater, WA

Median AQI 27 (Good). 93.5% of monitored days rated Good across this metro's EPA monitoring network.

Compiled by PlainAirData · August 4, 2026

27
Median AQI: 93.5%
Good-air days: 0
Unhealthy days: 92%
Cleaner than US metros

Olympia-Tumwater, WA posted a 2025 median AQI of 27 (Good) with 93.5% Good days

According to the U.S. EPA Air Quality System, the Olympia-Tumwater, WA CBSA recorded a median AQI of 27 across 293 monitored days in 2025, with 93.5% 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 Olympia-Tumwater, WA CBSA's 93.5% Good-day share places it cleaner than 92% of US metros in 2025.
Closest median-AQI peer: Aberdeen, SD (83.6% Good, median AQI 27) is the closest nationwide median-AQI peer to Olympia-Tumwater, WA.
2020–2025 Good-day shift: Olympia-Tumwater, WA's Good-day share moved +6.2 points from 2020 to 2025 (median AQI -1).
Median AQI: Median AQI: 27

Aggregated from EPA Air Quality System (2025), 293 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 27 with 93.5% of 293 monitored days in the Good band.

27
median AQI · Good: 93.5%
days rated Good: 92%
cleaner than US metros: 65
worst single reading

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

Olympia-Tumwater, WA metro's peak single-day AQI fell from 85 to 65 between the 2024 and 2025 EPA annual releases, a change of -20 points.

Insights: Olympia-Tumwater, WA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 27 over 293 measured days in 2025, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 274 Good days (94%), 19 Moderate (6%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 47 while the highest single-day reading hit 65 (Moderate). Metro residents averaged roughly 28.1 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 +6.2 points (measured against 362 monitored days in 2020 and 293 in 2025, so raw day counts are not comparable) and the median AQI moved -1 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 Aberdeen, SD (83.6% good, AQI 27); Albany, OR (80.0% good, AQI 27); Anchorage, AK (77.5% good, AQI 27).

Air Quality Summary

Median AQI

Good

Good Days

93.5%

274 of 293 days

Max AQI

Moderate

Health Grade

Excellent

90th pct: 47

AQI Day Breakdown (2025)

Distribution of 293 monitored days across EPA AQI categories.

Good

274

94%

Moderate

USG

Unhealthy

Very Unhealthy

Hazardous

Health Impact Assessment

Excellent

The Olympia-Tumwater, WA metro area's air quality is rated Excellent based on 93.5% 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

Compare against

Good-day share better than typical

Olympia-Tumwater, WA 93.5%

Aberdeen, SD 83.6%

Typical US metro 70.6%

Median AQI better than typical

Olympia-Tumwater, WA 27

Aberdeen, SD 27

Typical US metro 41

Unhealthy days / yr better than typical

Olympia-Tumwater, WA 0

Aberdeen, SD 0

Typical US metro 1

5-Year Air Quality Trend

Air quality is improving in the Olympia-Tumwater, WA metro. Highest Good-day share: 2021 (93.9%, 309 of 329 monitored days).

Year	Good	Moderate	Unhealthy	Median AQI	Max AQI
2020	316	43	3	28	242
2021	309	20	0	19	63
2022	309	36	2	28	157
2023	327	31	0	28	82
2024	338	24	0	26	85
2025	274	19	0	27	65

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Olympia-Tumwater, WA (27).

Aberdeen, SD

Median AQI 27 · 83.6% Good-day share

Albany, OR

Median AQI 27 · 80.0% Good-day share

Anchorage, AK

Median AQI 27 · 77.5% Good-day share

La Grande, OR

Median AQI 27 · 84.4% Good-day share

Sheridan, WY

Median AQI 27 · 89.1% Good-day share

Utica-Rome, NY

Median AQI 27 · 84.4% Good-day share

Metros with similar unhealthy-day exposure

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

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-Schenectady-Troy, NY

0 unhealthy-or-worse days · median AQI 41

Alexandria, LA

0 unhealthy-or-worse days · median AQI 37

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 27, rated "Good." 93.5% of monitored days (274 out of 293) 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 65.

Is air quality in Olympia-Tumwater, WA getting better or worse? ▼

Air quality in the Olympia-Tumwater, WA 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: 2021 at 93.9% (309 of 329 days). Lowest qualifying Good-day share: 2020 at 87.3% (316 of 362 days).

What does AQI 27 mean for health? ▼

An AQI of 27 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 47, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 65 (Moderate).

How does Olympia-Tumwater, WA compare to other metro areas? ▼

The Olympia-Tumwater, WA metro has 93.5% good air days. Similar metros: Aberdeen, SD (83.6% good), Albany, OR (80.0% good), Anchorage, AK (77.5% 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 Accessed 2026-07-06

Send the source-year summary or download its ready-to-use data card.

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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.