Washington Air Quality in October
Across 2019–2025, Washington's October air quality had a median AQI of 43 (Good) over 217 monitored days in the Washington-Arlington-Alexandria, DC-VA-MD-WV area. 0.0% of October days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 62.7% of days. The cleanest October on record here was 2025 (median AQI 36, 0 days above 100) and the worst was 2022 (median 48, 0 days above 100, peak AQI 64).
- Good: 65.4%
- Moderate: 34.6%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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How is the air in Washington in October?
Good on a typical day: median AQI 43 across 2019–2025, with 0.0% of October days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓65.4% of October days were Good (AQI 0–50), 34.6% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the October peak was 84.
- ✓Best October: 2025; worst October: 2022.
Frequently asked questions
What is the air quality like in Washington in October?▾
Across 2019–2025, the median daily AQI in Washington in October was 43 (Good). 65.4% of days were Good, 34.6% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is October a good time for outdoor exercise in Washington?▾
A typical October day in Washington sits in the Good range (median AQI 43), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of October days reached AQI 101+ in 2019–2025.
Which pollutant causes Washington's October air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 62.7% of October days in Washington. The highest October AQI recorded in 2019–2025 was 84 (Moderate), in 2022.
Washington October air quality, year by year
Washington October air quality by year (Washington-Arlington-Alexandria, DC-VA-MD-WV, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 42 | 0 | 63 | O3 |
| 2020 | 31 | 43 | 0 | 64 | PM2.5 |
| 2021 | 31 | 41 | 0 | 63 | PM2.5 |
| 2022worst | 31 | 48 | 0 | 64 | PM2.5 |
| 2023 | 31 | 47 | 0 | 84 | PM2.5 |
| 2024 | 31 | 45 | 0 | 74 | PM2.5 |
| 2025cleanest | 31 | 36 | 0 | 61 | O3 |
What October air means in Washington
A typical October day in Washington sits in the Good range (median AQI 43), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of October days reached AQI 101+ in 2019–2025.
October's median AQI of 43 is below Washington's whole-year median of 52, making it one of the area's cleaner periods. Nationally, the median October AQI across every EPA metro area (102,872 metro-days, 2019–2025) is 38, so Washington runs above the national October norm; 0.0% of its October days topped AQI 100 versus 1.3% nationally (below average).
October is part of Washington's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Washington
The latest EPA AirNow observation puts Washington's AQI at 41 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Washington air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Washington-Arlington-Alexandria, DC-VA-MD-WV), 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.