What Is the Air Quality in Napa, California?

Napa, California earns a B — air quality is reliably in the safe range for most residents most of the time, with a 5-year median AQI of 39. Sensitive groups will see occasional caution days, but the typical resident will not need to change behavior based on air quality.

Napa, California's 5-year median AQI of 39 is 2 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within California, Napa, California runs cleaner than the state average of 49 — a positive signal that local conditions (terrain, wind patterns, emission sources) are working in residents' favor.

For context within California: Humboldt, California currently holds the state's cleanest grade (A, AQI 28), while Inyo, California sits at the bottom (F, AQI 57).

Air quality in Napa, California has been improving over the past decade, with median AQI dropping by roughly 2.3 points per year. That is consistent with the broader national pattern — most U.S. metros have seen steady reductions in particulate and ozone pollution since the 2010s as cleaner vehicles and power plants come online.

In 2014, Napa, California posted a median AQI of 55. By 2021 that figure was 41 — a drop of 14 AQI points cleaner across 8 years of EPA records.

Across the past five years, this area has logged just 17 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 3 days per year, or roughly one every other month. That is a low count by national standards.

For most healthy adults, current air quality in this area does not require any change in behavior. People with severe asthma, COPD, or recent cardiac events should still keep an eye on daily AQI alerts, especially during wildfire season. Because PM2.5 penetrates deep into the lungs and bloodstream, an N95 or KN95 mask provides meaningful protection on smoky or high-particulate days — surgical masks do not.