The Santa Rosa monitor read 211 on Friday — “very unhealthy”, and by a wide margin the worst air anywhere within a hundred miles. The forecast says the weekend is the bad part. Fifteen miles east, the air is fine.
Smoke from the Woodside Fire on the Sonoma coast has settled over the Santa Rosa plain and the valley behind it. The Bay Area Air District’s monitor at Santa Rosa — nine miles from Kenwood and the nearest official station to these three towns — recorded fine-particulate air quality of AQI 211 on Friday. That is the “very unhealthy” band, two steps above the point at which healthy adults are told to take it easy. It read 165 on Thursday. Sonoma County’s health officer has an air quality advisory in force.
How long it lasts
The official forecast, in order: Saturday AQI 152, still “unhealthy”; Sunday and Monday moderate; Tuesday good. So the weekend is the part to plan around, and the worst of it should be behind us by the start of next week — assuming the fire keeps being held, which at 30% containment on Friday morning is a reasonable but not a safe assumption.
Smoke does not spread evenly, and it is worth understanding why this is landing on us in particular. The fire is more than fifty miles away on the coast. Its plume has drifted inland and then sunk into the low ground — the Santa Rosa plain and the Sonoma Valley are a basin, and overnight inversions put a lid on it, which is why the worst readings come in the small hours and early morning. The same smoke is now reaching Sacramento, where the air district has called a Spare the Air day.
Where the clean air is
This is the useful part, and the numbers are startling. Every official reading within 130 miles of Kenwood on Friday, ranked — and note that Santa Rosa is not merely the worst, it is nearly four times the next worst:
| Where | Miles | AQI | Category |
|---|---|---|---|
| Santa Rosa (us) | 9 | 211 | Very unhealthy |
| Napa | 15 | 55 | Moderate |
| San Rafael | 31 | 57 | Moderate |
| Concord | 41 | 52 | Moderate |
| San Francisco | 46 | 53 | Moderate |
| Ukiah | 62 | 48 | Good |
| Auburn | 86 | 24 | Good |
| San Lorenzo Valley | 95 | 27 | Good |
The practical upshot: you do not have to go far. Napa is fifteen minutes over the Mayacamas and was reading 55 against our 211 — the ridge is doing real work. South into Marin, or across to Contra Costa, is much the same. For genuinely clean air, Ukiah up 101 was the nearest “good” reading, with the Sierra foothills and the Santa Cruz mountains cleaner still.
Two cautions before you get in the car. These are reporting-area readings, not your street, and smoke moves — check AirNow’s fire and smoke map before you drive rather than trusting a table from this morning. And a car is a reasonably good air cleaner in its own right if you set the ventilation to recirculate, so the drive itself is not the problem.
If you are staying put
The county’s guidance is the standard set, and it works: windows and doors closed, air conditioning and car ventilation on recirculate, fresh-air intake shut, filters clean. Stay hydrated. Do nothing that adds to it — no mowing, no leaf blowing, no barbecuing, no wood fires. Older adults, pregnant women, children and anyone with heart or lung trouble feel this first and worst.
On masks: a cloth or surgical mask is close to useless against particles this fine. An N95 or P100, fitted properly against the face, is not.
And the cheapest genuinely effective thing you can do indoors is to tape a MERV-13 furnace filter to the back of a box fan — the arrow on the filter pointing into the fan. It costs about thirty dollars, it noticeably clears a room, and it is the single most cost-effective piece of smoke advice there is. Run it while you are awake rather than overnight unattended.
A correction, and what we changed
We owe readers a plain account of this. Earlier on Friday this paper published an air quality figure of around AQI 50 for the valley and said healthy people would notice nothing. That was wrong. The number came from a gridded forecast model, and while checking a follow-up we found the model was not resolving the smoke plume at all: it returned nearly identical readings for the entire county, including at the fire itself, at a moment when the nearest real monitor was reading 211.
The earlier report has been corrected. More to the point, the live air quality figure on our front page and on the fire, weather and water dashboard now comes from the Bay Area Air District’s actual monitors rather than from a model, refreshed every half hour, and it names the station it came from. The model survives only as a fallback if the monitor feed goes down, and it is labelled as modelled when it appears. A number that understates the danger precisely when the danger is real is worse than no number at all.
There is still no ground-level air monitor in Kenwood, Glen Ellen or Oakmont. Santa Rosa, nine miles away and slightly lower, is the closest true reading available. If you can smell smoke, believe your nose over any number, including ours.
Sources: AirNow reporting-area file (Bay Area Air District observations and forecasts), retrieved 31 July 2026; Sonoma County Department of Health Services air quality advisory; CAL FIRE incident data. Distances are straight-line from Kenwood.