Bad Air Days in Maui County, Hawaii: under 1 a Year

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 750 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 July and January and March and August. Averaged over 2016 to 2025.

What to buy, and what not to

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 under 1 bad days a year; in 2016 to 2025, under 1. Not much has changed. The worst recent year was 2019, with 4 bad days on 362 monitored days.

Date	AQI	Main pollutant
2019-07-11	171	PM2.5
2023-01-01	152	PM2.5
2016-03-10	130	PM2.5
2019-07-14	127	PM2.5
2019-07-12	123	PM2.5

An ordinary day in Maui

Across 3,597 monitored days from 2016 to 2025, the air in Maui County rated Good on 96% of them, more often than the 72% typical of monitored counties, and Moderate on 4%. The median day sat at AQI 23; one day in ten went above 37.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)100%3,597 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	360	353	7	0	0	21	69
2024	364	363	0	1	0	21	101
2023	347	344	2	1	1	20	152
2022	361	357	4	0	0	21	58
2021	363	361	2	0	0	21	63
2020	349	343	6	0	0	21	61
2019	362	339	19	4	1	20	171
2018	361	347	14	0	0	25	76
2017	364	332	32	0	0	28	88
2016	366	324	41	1	0	28	130
2015	365	310	55	0	0	33	77
2014	341	305	35	1	0	29	136
2013	362	285	77	0	0	37	81
2012	349	302	47	0	0	33	68
2011	320	283	37	0	0	29	65
2010	343	322	21	0	0	24	78

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

Hawaii compared

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.