Lewis County, Washington
AQI 18 · Good18
Median AQI
42
90th Percentile
74
Max AQI
209
Days with Data
Ranked #4 of 31 counties in Washington (by median AQI, lower is better)
Monthly Median AQI — 2025
Click a bar to view that month's details
18
Median AQI
42
90th Percentile
74
Max AQI
209
Days with Data
Ranked #4 of 31 counties in Washington (by median AQI, lower is better)
Click a bar to view that month's details