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.
- 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
Olympia-Tumwater, WA sits in the upper Good-day tercile among EPA CBSA metros on this site (93.5% of 293 monitored days). On the EPA scale the metro runs good, among the cleanest 10% of US metros, with a median AQI of 27 and 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.
Annual release change
What changed in the 2025 EPA annual release
- 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.
Olympia-Tumwater, WA sits in the upper Good-day tercile among EPA CBSA metros on this site (93.5% of 293 monitored days). Signature read: 93.5% Good-day share (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 27 over 293 measured days in 2025 (Good / Excellent). The monitored-day split lands at 274 Good (94%), 19 Moderate (6%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 47; the highest single-day reading hit 65 (Moderate).
Across 2020–2025, Good-day share shifted +6.2 points and median AQI moved -1 (improving). No Unhealthy-tier days appear 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
27
Good
Good Days
93.5%
274 of 293 days
Max AQI
65
Moderate
Health Grade
Excellent
90th pct: 47
AQI Day Breakdown (2025)
Distribution of 293 monitored days across EPA AQI categories.
Good
274
94%
Moderate
19
6%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
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
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
Frequently Asked Questions
How many unhealthy air days does Olympia-Tumwater, WA have? ▼
What is the air quality in the Olympia-Tumwater, WA metro area? ▼
Is air quality in Olympia-Tumwater, WA getting better or worse? ▼
What does AQI 27 mean for health? ▼
How does Olympia-Tumwater, WA compare to other metro areas? ▼
What is the 90th percentile AQI for Olympia-Tumwater, WA? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Olympia-Tumwater, WA, 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, Olympia-Tumwater, WA · 2020–2025