Today | Weather | Monday, September 21, 2026

Weather in Seattle, Washington

10:54 AM
Now
Cloudy Weather
61° F
Feels Like 63°
Precipitation 0 %
Wind 5 mph
UV Index (0 - 11+) 2
Humidity 81 %
Today
Cloudy Weather
Day 66°
Night 55°
Precipitation 0 %
Wind 5 mph
UV Index (0 - 11+) 3

Seattle Weather Forecast Updated

53 minutes ago
Last updated on
Weather Forecast History
Last Year's Weather on This Day (September 21, 2025)
Cloudy Night

Day

64°

Night

52°

Wind

5 mph

Precipitation

5 %

Air Quality in Seattle

NOW
21 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 2.74 µg/m³
PM10 3.94 µg/m³
O3 0.022 ppm
NO2 2.5 ppb
SO2 0.3 ppb
CO 0.12 ppm
NH3 0.41 µg/m³
NO 0.48 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.52.74 µg/m³
PM103.94 µg/m³
O343.54 µg/m³
NO24.74 µg/m³
SO20.72 µg/m³
CO134.96 µg/m³
NH30.41 µg/m³
NO0.48 µg/m³