Bad Air Days in Grays Harbor County, Washington: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 568 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (100% particle days).

The bad-air season here

Most bad days here fall in September and August. Averaged over 2016 to 2025.

Is a purifier worth it here?

Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
On the odd bad day, check AirNow and keep windows shut.

The worst days on file

In 2000 to 2009 this county averaged 0 bad days a year; in 2016 to 2025, 2. Not much has changed. The worst recent year was 2020, with 8 bad days on 366 monitored days.

Date	AQI	Main pollutant
2020-09-14	242	PM2.5
2020-09-12	238	PM2.5
2020-09-13	237	PM2.5
2020-09-11	235	PM2.5
2020-09-15	233	PM2.5

The air on a normal day

Across 3,638 monitored days from 2016 to 2025, the air in Grays Harbor County rated Good on 92% of them, more often than the 72% typical of monitored counties, and Moderate on 7%. The median day sat at AQI 25; one day in ten went above 45.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)100%3,638 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	355	10	0	0	22	76
2024	366	353	13	0	0	20	64
2023	365	339	26	0	0	23	80
2022	365	340	24	1	0	22	112
2021	365	347	18	0	0	26	82
2020	366	330	28	8	7	27	242
2019	352	327	25	0	0	27	62
2018	365	324	37	4	3	29	168
2017	365	313	49	3	1	27	162
2016	364	330	34	0	0	28	75
2015	343	303	40	0	0	29	68
2014	365	319	46	0	0	27	71
2013	365	276	89	0	0	28	75
2012	366	319	47	0	0	27	83
2011	363	331	32	0	0	21	64
2010	365	355	10	0	0	22	76

*2025 may be a partial year in EPA's file.

Elsewhere in Washington

How this is counted

A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day.