Spokane Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Spokane (Spokane-Spokane Valley, WA area) was September 13, 2020, when the daily AQI reached 957 (Hazardous), set by fine particulate matter (PM2.5), in wildfire smoke season. Across 2,557 monitored days in 2019–2025, 10 of the 10 worst days were Unhealthy (AQI 151+) or worse; 10 of the 10 were driven by fine particulate matter (PM2.5), and 6 of them fell in 2020. The cleanest day was April 29, 2024 at AQI 9 (Good); the 10 best days span 3 different years.
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When were Spokane's worst and best air quality days?
Worst: September 13, 2020, AQI 957 (Hazardous, PM2.5). Best: April 29, 2024, AQI 9 (Good). Based on 2,557 EPA-monitored days in the Spokane-Spokane Valley, WA area, 2019–2025.
- ✓10 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 223 (Very Unhealthy).
- ✓Fine particulate matter (PM2.5) drove 10 of the 10 worst days.
- ✓2020 accounts for 6 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Spokane?▾
September 13, 2020: the Spokane-Spokane Valley, WA area's daily AQI hit 957 (Hazardous), driven by fine particulate matter (PM2.5), in wildfire smoke season. That is the highest of 2,557 monitored days in 2019–2025.
What was the best air quality day in Spokane?▾
April 29, 2024, with a daily AQI of 9 (Good). The daily AQI is the highest reading from any monitor in the area, so even the cleanest day reflects the area's worst monitor.
What was Spokane's worst air quality day in 2025?▾
September 6, 2025, AQI 243 (Very Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season.
Which pollutant causes Spokane's worst air days?▾
Fine particulate matter (PM2.5) set the AQI on 10 of the 10 worst days. The tables above list the defining pollutant for every day.
Spokane's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Spokane-Spokane Valley, WA area (EPA AQS). The daily AQI is the highest reading from any monitor in the area that day.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2020 page) | 957 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 2 | (2020 page) | 709 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 3 | (2020 page) | 642 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 4 | (2023 page) | 447 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 5 | (2020 page) | 424 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 6 | (2023 page) | 277 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 7 | (2025 page) | 243 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 8 | (2020 page) | 240 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 9 | (2021 page) | 223 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 10 | (2020 page) | 223 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
Worst day of each year in Spokane
The single highest-AQI day in each year on record. Click a year for its full month-by-month statistics.
| Year | Worst day | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 2019 | 146 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2020 | 957 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2021 | 223 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2022 | 185 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2023 | 447 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2024 | 106 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2025 | 243 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
Spokane's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Spokane-Spokane Valley, WA area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2024 page) | 9 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 2 | (2024 page) | 9 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 3 | (2025 page) | 10 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2025 page) | 11 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 5 | (2024 page) | 11 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 6 | (2025 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 7 | (2025 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2024 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2024 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 10 | (2021 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
Right now in Spokane
The latest EPA AirNow observation puts Spokane's AQI at 26 (PM2.5). The days above are historical records, not today's reading.
View current Spokane air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Spokane-Spokane Valley, 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.