Seattle air quality now

United States · The summary is refreshed every 15 minutes.

October 22

The air is clean now

Seattle

7°C

Partly cloudy

33AQI

1014hPa

Atmospheric
pressure

86%

Humidity

Seattle, October 21, 2026: daily mean PM2.5 10 µg/m³ (10 sensors), level “Low” — as in the Atmy Data Hub. Now (11:00 local time): 6.0 µg/m³. Open methodology and data in JSON: Methodology and data sources · JSON

Right now in Seattle, PM2.5 averages 6.0 µg/m³ — “good” on the US EPA scale (approximate, from hourly readings). Mean of 10 sensors on the Atmy network, readings from 10:45–10:47 local time (17:45–17:47 UTC), summary prepared at 11:00 local time. Median: 6.0 µg/m³; range across sensors: 0.0–11.0 µg/m³.

In Seattle the air is good right now (approximate, US EPA scale). From 22:00 to 11:00 local time the city mean PM2.5 fell from 13.7 to 6.0 µg/m³.

The weather data do not point to a clear reason for this level.

Weather now: partly cloudy, 7°C, wind 1 m/s, humidity 86%. By 14:00 the wind is expected to pick up to 4 m/s, which may clear the air.

Written automatically at 11:00 local time (18:00 UTC) from sensor measurements and the weather forecast. Values are approximate; hypotheses are marked.

4 km/h

Wind, NE

0 mm

Precipitation today

Seattle: air quality for the completed day

Metric: PM2.5, µg/m³ · Color scale: EPA AQI · October 21, 2026 · 00:00–24:00 UTC

10 µg/m³ Low

Daily mean PM2.5 on October 21, 2026 (00:00–24:00 UTC): 10 µg/m³ from 10 sensors that passed the quality check — the same value as in the Atmy Data Hub.

LowModerateElevatedHighVery highExtremely high

Air Quality in United States for the Completed Day

Metric: PM2.5, µg/m³ · Color scale: EPA AQI · October 21, 2026 · 00:00–24:00 UTC

Portland →9 µg/m³Bellevue →9 µg/m³
LowModerateElevatedHighVery highExtremely high

Source: Air monitoring system atmy.ai

Seattle: PM2.5 by month

Metric: PM2.5, µg/m³ · Color scale: EPA AQI

Mean
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
This month
6
6
6
6
10
5
3
5
5
3
5
11
6
8

Monthly means of quality-checked sensors, as in the Data Hub trend; the current month is still incomplete, “-” means no data.

Pollution accumulation index now

28%An estimate of weather conditions · not a PM2.5 forecast

Now2838
11.0019.0002.0010.00

Pollution accumulation forecast

Today — October 22

12°/6°

Index by time of day

54/100Moderate

  1. 54/100Night
  2. 46/100Morning
  3. 7/100Day
  4. 24/100Evening

Friday — October 23

13°/4°

Index by time of day

57/100Moderate

  1. 57/100Night
  2. 43/100Morning
  3. 9/100Day
  4. 26/100Evening

Saturday — October 24

14°/5°

Index by time of day

58/100Moderate

  1. 58/100Night
  2. 39/100Morning
  3. 8/100Day
  4. 20/100Evening

Sunday — October 25

17°/7°

Index by time of day

52/100Moderate

  1. 52/100Night
  2. 39/100Morning
  3. 8/100Day
  4. 23/100Evening

Monday — October 26

15°/8°

Index by time of day

56/100Moderate

  1. 56/100Night
  2. 43/100Morning
  3. 7/100Day
  4. 22/100Evening

Tuesday — October 27

13°/9°

Index by time of day

51/100Moderate

  1. 51/100Night
  2. 42/100Morning
  3. 9/100Day
  4. 24/100Evening

Forecast of conditions that trap pollution near the surface

Weather

7°

Partly cloudy. Feels like 5°C

  1. MorningPartly cloudy7°C86%
  2. DayCloudy12°C84%
  3. EveningCloudy10°C79%

Wind

4km/hWind from the NE

4km/hWind gusts

Wind force: 1

Gusts up to 30 km/h are expected.

10-day weather forecast for Seattle

United States

  1. TodayOct 22Cloudy12°C6°C
  2. FriOct 23Clear13°C4°C
  3. SatOct 24Cloudy14°C5°C
  4. SunOct 25Cloudy17°C7°C
  5. MonOct 26Cloudy15°C8°C
  6. TueOct 27Rain13°C9°C
  7. WedOct 28Cloudy14°C7°C
  8. ThuOct 29Cloudy16°C6°C
  9. FriOct 30Cloudy13°C7°C
  10. SatOct 31Cloudy13°C7°C

Where in Seattle is the air worse?

See all sensors

Highest current reading: 11.0 µg/m³ (W Olympic Pl, Seattle). Lowest: 0.0 µg/m³ (201 Elliott Ave W). The list shows every sensor, highest first.

  1. W Olympic Pl, Seattle →11 µg/m³
  2. Salmon Bay Park →9 µg/m³
  3. Alaska Junction →9 µg/m³
  4. holmdell →6 µg/m³
  5. Crown Hill →6 µg/m³
  6. MT-Co-op →6 µg/m³
  7. Seattle Duwamish #1 →5 µg/m³
  8. Maple Leaf, Seattle, WA →4 µg/m³
  9. Jon & Leska’s →4 µg/m³
  10. 201 Elliott Ave W →0 µg/m³

Source: atmy.ai monitoring network

Who provides the data

Sensors in the summary by network: AirGradient — 10 sensors.

Atmy shows the networks’ readings after the Data Hub’s quality check: test devices and sensors that fail it are left out.

United States: sensors in total

41

  1. BellevueUnited States

    4

  2. PortlandUnited States

    4

  3. RenoUnited States

    3

Cities with the most sensors

All sensors on the map, by city as the map assigns them; the city’s values count only the sensors that pass the Data Hub’s quality check.

Air quality calendar: Seattle

Daily mean PM2.5 of the city sensors, µg/m³

Click a day to see its date and value.

LowModerateElevatedHighVery highExtremely high

Widget for your site

A card with the current PM2.5 in Seattle: it is refreshed every 15 minutes and links to this page. Paste the code into your site.

Air quality in Seattle now — Atmy

United States · City ranking · All pilot cities

Questions

What was the air quality in Seattle over the last completed day?

Daily mean PM2.5 on October 21, 2026 (00:00–24:00 UTC): 10 µg/m³ from 10 sensors that passed the quality check — the same value as in the Atmy Data Hub.

What is the air quality in Seattle right now?

Right now in Seattle, PM2.5 averages 6.0 µg/m³ — “good” on the US EPA scale (approximate, from hourly readings). Mean of 10 sensors on the Atmy network, readings from 10:45–10:47 local time (17:45–17:47 UTC), summary prepared at 11:00 local time. Median: 6.0 µg/m³; range across sensors: 0.0–11.0 µg/m³.

Is it safe to be outdoors in Seattle now?

The current level is “good” (US EPA scale, approximate). Air quality is satisfactory; no restrictions are recommended. This is the standard guidance of the scale, not medical advice.

Where in Seattle is the air worse?

Highest current reading: 11.0 µg/m³ (W Olympic Pl, Seattle). Lowest: 0.0 µg/m³ (201 Elliott Ave W). The list shows every sensor, highest first.

Where do these data come from?

From Atmy sensors and connected public networks (citizen, experimental and government monitors), aggregated by Atmy. Values are approximate; see the methodology.

How often is this page updated?

The summary is rebuilt every 15 minutes from the latest reading of each sensor, each no older than one hour.

Is the air in Seattle polluted?

Over the last 365 days with data, the mean daily PM2.5 in Seattle was 6.2 µg/m³ — 1.2 times the WHO annual guideline (5 µg/m³). Over the last 30 days: 6.8 µg/m³. From Atmy's archive of daily city means.

When is the air in Seattle cleanest?

In Atmy's daily archive, the cleanest month of the last year was June 2026: 3.2 µg/m³ on average.

When is the air in Seattle most polluted?

The most polluted month of the last year was August 2026: 10.6 µg/m³ on average.

Is the air in Seattle worse in the heating season?

From November to March the mean daily PM2.5 was 6.3 µg/m³, from June to August 6.5 µg/m³ (last 365 days).

Data

Where do these data come from?

The daily value is the Data Hub’s: the mean of the city’s sensors that passed the nightly quality check, each with at least 12 valid hours, and only with sensors at four places 500 m apart; days are UTC.

“Now” uses the same sensors and rule: the mean of their latest readings, each at most 60 minutes old, shown only with sensors at four places 500 m apart reporting.

Source: public Atmy monitoring data. Methodology and data sources · Data terms