Skip to main content
AirHistory

Sonoma, California Air Quality Today

AirHistory tracks long-run EPA monitoring rather than live readings, so for the live number check AirNow.gov below. As a baseline, Sonoma, California's most recent EPA year (2023) posted a median AQI of 33 (Good) against a 5-year median of 36 and an overall Grade of B. The dominant pollutant is Ground-Level Ozone, which tells you which days are most likely to spike.

Check Today's Live AQI in Sonoma, California

AirHistory is built on 10 years of EPA Air Quality System records, so it shows you what air quality in Sonoma, California typically looks like — not the live reading for this exact hour. For today's real-time AQI, check AirNow.gov (the EPA's official live index) or the AirNow Fire and Smoke Map during wildfire season.

That said, the history is the best predictor of a normal day. In 2023, Sonoma, California posted a median AQI of 33 (Good), with 323 "Good" days and 2 days that crossed into "Unhealthy for Sensitive Groups" or worse. The dominant pollutant, Ground-Level Ozone, is the one most likely to push today's number up — Ground-level ozone forms when sunlight reacts with vehicle exhaust and industrial emissions. It is worst on hot, sunny, stagnant summer days. Ozone irritates the lungs, triggers asthma attacks, and reduces lung function — even healthy adults can feel chest tightness and shortness of breath after exercising in elevated ozone.

Sonoma, California Air Quality Snapshot

Air Quality GradeB71/100
5-Year Median AQI36 (Good)
Most Recent Median AQI (2023)33 (Good)
Dominant PollutantGround-Level Ozone
10-Year TrendImproving (-0.55 AQI/yr)
Unhealthy Days (last 5 yr)9
National Rank (cleanest = #1)#261 of 1,020 (26th cleanest percentile)
California Rank#6 of 53

What Does the B Grade Mean?

Sonoma, 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 36. Sensitive groups will see occasional caution days, but the typical resident will not need to change behavior based on air quality.

Sonoma, California's 5-year median AQI of 36 is 5 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within California, Sonoma, 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).

What's in Sonoma, California's Air?

The dominant pollutant in Sonoma, California is Ground-Level Ozone. Ground-level ozone forms when sunlight reacts with vehicle exhaust and industrial emissions. It is worst on hot, sunny, stagnant summer days. Ozone irritates the lungs, triggers asthma attacks, and reduces lung function — even healthy adults can feel chest tightness and shortness of breath after exercising in elevated ozone.

Days by Dominant Pollutant (2023)

PollutantDays as DominantShare of Year
Ground-Level Ozone23665%
Fine Particulate Matter (PM2.5)12735%
Coarse Particulate Matter (PM10)10%
Carbon Monoxide10%

Is the Air Getting Better or Worse?

Air quality in Sonoma, California has been improving over the past decade, with median AQI dropping by roughly 0.6 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, Sonoma, California posted a median AQI of 42. By 2023 that figure was 33 — a drop of 9 AQI points cleaner across 10 years of EPA records.

Year-by-Year AQI in Sonoma, California

YearMedian AQIGood DaysUnhealthy DaysDominant Pollutant
2014422570PM2.5
2015372930Ozone
2016343230Ozone
2017412675Ozone
20183930413Ozone
2019363180Ozone
2020362907PM2.5
2021372830PM2.5
2022362860Ozone
2023333232Ozone

Health Context for Sonoma, California

Across the past five years, this area has logged just 9 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 2 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 ozone peaks in the afternoon on hot sunny days, plan outdoor exercise for early morning or after sunset on bad-air days.

How This Grade Is Calculated

The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.

View full Sonoma, California profile →All California cities →Air quality checker →Methodology →

More about Sonoma, California

Sonoma, California has an Air Quality Grade of B (good) with a 5-year median AQI of 36. The dominant pollutant is Ground-Level Ozone, and air quality has been improving over the past decade.

This answer pulls from the EPA Air Quality System (AQS), the authoritative federal source for U.S. air quality and pollution monitoring. The headline number above is the direct answer; what follows is the additional context most readers need to use the answer for a real decision rather than just a fact lookup.

A practical caveat: the headline answer above reflects the most recent the EPA Air Quality System (AQS) vintage; underlying data is often revised for months after first publication, and the right reference for any specific decision is whichever vintage is current at the time of the decision. The as-of date is stamped on every page.

Source: EPA Outdoor Air Quality Data, 2026.