Seattle air quality
Washington, United States · Live AQI and hourly forecast for the next 5 days · updated Sat 4:00 PM local time
Good
Great air. A perfect time to be outside.
- Next 24 hours
- 36–39US AQI, highest around Sun 12:00 PM
- Best time outside
- Sat 4:00 PM–7:00 PMUS AQI about 36
- PM2.5 vs WHO guideline
- 0.5×7.2 µg/m³ over 24 h, guideline 15
- Cigarette equivalent
- ≈ 0.3 a dayBerkeley Earth rule of thumb
- European AQI
- Fairlevel 2 of 6
Loading the live globe…
Pollutants in Seattle right now
| Pollutant | Now | Next 24 h vs WHO | US AQI band |
|---|---|---|---|
| Fine particles (PM2.5) | 6.0 µg/m³ | 0.5× | Good |
| Coarse particles (PM10) | 8.1 µg/m³ | 0.2× | Good |
| Nitrogen dioxide (NO2) | 3.6 µg/m³ | 0.6× | Good |
| Ozone (O3) | 79 µg/m³ | 0.6× | Good |
| Sulphur dioxide (SO2) | 1.5 µg/m³ | 0.1× | Good |
| Carbon monoxide (CO) | 136 µg/m³ | 0.0× | Good |
| Desert dust | 0 µg/m³ | ||
| Smoke and haze (aerosol optical depth) | 0.08 | ||
| UV index | 1.4 |
“Next 24 h vs WHO” compares the forecast with the World Health Organization’s 2021 guideline levels: 24-hour means of 15 µg/m³ for PM2.5, 45 for PM10, 25 for NO2, 40 for SO2 and 4 mg/m³ for CO, and 100 µg/m³ over 8 hours for ozone. Above 1× is above the guideline.
Next 48 hours
Hourly US AQI. Highest 64 around Mon 2:00 PM, lowest 36 around Sat 4:00 PM.
5-day air quality forecast for Seattle
Daily range of the hourly US AQI, from lowest to highest, on a scale of 0 to 150.
| Day | US AQI | At worst | PM2.5 avg | |
|---|---|---|---|---|
| Sat, Sep 26 | 26–43 | 6.5 | ||
| Sun, Sep 27 | 36–45 | 8.5 | ||
| Mon, Sep 28 | 47–64 | 15 | ||
| Tue, Sep 29 | 34–61 | 5.9 | ||
| Wed, Sep 30 | 26–36 | 7.0 |
Common questions about the air in Seattle
Is the air in Seattle safe today?
Yes. Right now the US AQI in Seattle is 36, which counts as good. Great air. A perfect time to be outside.
When is the best time to be outside in Seattle?
Sat 4:00 PM–7:00 PM. That is the cleanest stretch in the next 24 hours, with the US AQI averaging about 36. The worst hour is around Sun 12:00 PM, at 39.
What is the main pollutant in Seattle?
Ozone (O3). It drives the index right now, at 79 µg/m³. Formed by sunlight acting on traffic and plant emissions. Highest on hot, still afternoons, often downwind of cities.
How does Seattle's air compare with the WHO guideline?
Within the guideline. Over the next 24 hours PM2.5 averages about 7.2 µg/m³, against the World Health Organization's 24-hour guideline of 15 µg/m³. The other pollutants stay within their guideline levels.
How many cigarettes is a day of Seattle's air?
About 0.3 cigarettes. Over the next 24 hours PM2.5 averages about 7.2 µg/m³. By Berkeley Earth's rule of thumb, 22 µg/m³ breathed for a day is roughly one cigarette.
Will air quality in Seattle improve this week?
Wednesday looks cleanest. Its AQI peaks at 36, against 64 on Monday, the worst day in the forecast.
Measured near Seattle
| Station | PM2.5 µg/m³ | Measured |
|---|---|---|
| Seattle-10th & Weller AirNow, reference monitor | 5.4 | Sat 3:00 PM |
| Seattle-Beacon Hill AirNow, reference monitor | 0.7 | Sat 3:00 PM |
| Seattle-Duwamish AirNow, reference monitor | – | Sat 3:00 PM |
Air quality near Seattle
- Vancouver 195 km N
- Portland 234 km S
- Calgary 710 km NE
- Edmonton 907 km NE
- Sacramento 1,006 km S
- San Francisco 1,093 km S
About this forecast
Forecast from CAMS global via Open-Meteo: the Copernicus Atmosphere Monitoring Service (CAMS) model at about 40 km resolution (10 km inside Europe), refreshed twice a day. Models smooth out street-level peaks, so busy roads and industrial sites can be worse than shown; ground stations, where there are any nearby, show what monitors actually measure. The US AQI follows the US EPA scale and the European AQI the EEA bands. Readings for 47.61°N, 122.33°W, updated 2026-09-26 23:00 UTC.