Seattle Air Quality in 2023
In 2023, Seattle's air quality (Seattle-Tacoma-Bellevue, WA area) had a median daily AQI of 50 (Good) across 365 monitored days. 7 days (1.9%) reached Unhealthy for Sensitive Groups or worse, 186 were Good, and the year's peak AQI was 195 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 242 of those days. The cleanest month of 2023 was April (median AQI 44, 0 days above 100) and the worst was August (median 52, 4 days above 100, peak 175).
- Good: 51.0%
- Moderate: 47.1%
- Unhealthy for Sensitive Groups: 1.1%
- Unhealthy or worse: 0.8%
Extra Protection for Seattle Homes
Air quality in Seattle is moderate (AQI 54), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
As an Amazon Associate, we earn from qualifying purchases.
How was Seattle's air quality in 2023?
Good on a typical day: median AQI 50, with 7 days above AQI 100 out of 365 monitored — the 5th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2023: 195 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 242 days.
- ✓Cleanest month: April; worst: August.
Frequently asked questions
What was the average AQI in Seattle in 2023?▾
EPA's Air Quality System puts Seattle's (Seattle-Tacoma-Bellevue, WA) median daily AQI for 2023 at 50, which is Good. 7 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 195.
Which month had the worst air quality in Seattle in 2023?▾
The cleanest month of 2023 was April (median AQI 44, 0 days above 100) and the worst was August (median 52, 4 days above 100, peak 175).
Was 2023 a good or bad year for Seattle's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2023 ranks 5th cleanest by days above AQI 100. 2023's median of 50 is in line with the area's typical annual median of 49.
Seattle month by month in 2023
Seattle air quality month by month, 2023 (Seattle-Tacoma-Bellevue, WA, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 53 | 0 | 76 | PM2.5 |
| February | 28 | 52 | 0 | 76 | PM2.5 |
| March | 31 | 47 | 0 | 77 | PM2.5 |
| Aprilcleanest | 30 | 44 | 0 | 60 | O3 |
| May | 31 | 50 | 0 | 62 | PM2.5 |
| June | 30 | 45 | 1 | 112 | PM2.5 |
| July | 31 | 43 | 2 | 195 | O3 |
| Augustworst | 31 | 52 | 4 | 175 | O3 |
| September | 30 | 47 | 0 | 71 | PM2.5 |
| October | 31 | 52 | 0 | 87 | PM2.5 |
| November | 30 | 63 | 0 | 92 | PM2.5 |
| December | 31 | 54 | 0 | 85 | PM2.5 |
How 2023 compares
Among the 7 years EPA has published for the area (2019–2025), 2023 ranks 5th cleanest by days above AQI 100.
2023's median of 50 is in line with the area's typical annual median of 49.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Seattle
The latest EPA AirNow observation puts Seattle's AQI at 54 (PM2.5). The figures above are multi-year annual statistics, not today's reading.
View current Seattle air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Seattle-Tacoma-Bellevue, WA), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.