Right now: Stockton is at 51, moderate.
Is the air safe to breathe in Stockton today?
In Stockton, BreatheCheck reads 51 as Go. The cutoffs: go below 101, keep it short and easy from 101 to 150, move it indoors above 150. These are our own thresholds, drawn on the EPA bands — EPA itself classifies 101–150 as Unhealthy for Sensitive Groups and does not tell you how long to stay out.
Go AQI 0–100
Normal outdoor plans. No change needed.
Short & unloaded AQI 101–150
A 20-minute dog walk, not a 2.5-hour run. Keep it brief and easy.
Don’t go AQI 151+
Move it indoors. Above 200 that becomes everyone, not just sensitive groups.
Above 200 this stops being a personal call: everyone indoors.
Duration and intensity are two separate dials
| Under 20 min | 20–60 min | Over an hour | |
|---|---|---|---|
| Easy | Go | Go | Go |
| Moderate | Go | Go | Go |
| Hard | Go | Go | Go |
Go Every combination lands the same way at this reading — a hard hour is no different from an easy twenty minutes. The two dials separate above 80.
Where people actually draw the line
All the thresholds people reported, and who reported them
- 60 Asthmatic runnerone runner’s own 156-run log
- 75–100 Daycare / schoolparents and staff in one r/toddlers thread, Aug 2025 — not a published rule
- 100 Parentcommunity-reported, escalating at 150 and 200
- 110 Runnercommunity-reported
If you’re staying in, filter the room you’re actually in
The Delta vent, and the nights it closes
Marine air reaches the San Joaquin Valley floor through one opening. The Carquinez Strait, the Central Valley’s only natural outlet to the sea, carries it inland across the Delta and past the city as the Delta breeze, strongest from June through September. Stockton sits at the valley’s open northern end, in the Delta that strait drains; the far southern end of the same trough, walled off toward the Mojave, has no equivalent gap. The vent is also the part that fails. When high pressure settles over the coast and shuts down onshore flow, the valley keeps whatever it is holding until the pattern breaks.
The pollutant the air district plans around is PM2.5, and the season it plans around is winter rather than fire season. On a still, clear night the valley floor cools, a warmer layer settles over it, and residential wood smoke has nowhere to go. The San Joaquin Valley Air Pollution Control District runs Check Before You Burn from November 1 through the end of February, issuing one of three declarations per county each day under Rule 4901: no burning, no burning unless registered, or burning discouraged.
Tule fog forms on those same capped nights, so the fog and the wood smoke tend to arrive together. The fog is not the pollutant. It is the visible half of a lid the number can only report. What sits under it runs year-round: an inland deepwater port at the head of a 41-mile ship channel, in a county both I-5 and Highway 99 cross end to end.
Where this number sits
Of the 121 US metros reporting to us right now, Stockton is number 29 and number 6 of the 12 we track in California. The pollutant driving it today is PM10.
Nearby metros we also measure, and what they read at the same hour:
- Sacramento, CA — 44 miles away, AQI 38
- San Jose, CA — 54 miles away, AQI 51
- Oakland, CA — 55 miles away, AQI 48
- Fresno, CA — 118 miles away, AQI 70
Where this reading comes from
AirNow’s Stockton reporting area, about 1.1 miles from the metro centre.
What has air quality in Stockton actually been?
2 of the 30 days we have recorded so far went above AQI 100.
| Date | Daily max AQI | EPA band | Hours read |
|---|---|---|---|
| 72 | Moderate | 22 | |
| 196 | Unhealthy | 23 | |
| 63 | Moderate | 23 | |
| 76 | Moderate | 23 | |
| 105 | Unhealthy for Sensitive Groups | 23 | |
| 66 | Moderate | 22 | |
| 55 | Moderate | 23 | |
| 49 | Good | 23 | |
| 47 | Good | 23 | |
| 49 | Good | 23 | |
| 46 | Good | 23 | |
| 53 | Moderate | 24 | |
| 52 | Moderate | 23 | |
| 59 | Moderate | 23 | |
| 55 | Moderate | 23 | |
| 52 | Moderate | 23 | |
| 57 | Moderate | 23 | |
| 82 | Moderate | 22 | |
| 60 | Moderate | 23 | |
| 86 | Moderate | 23 | |
| 61 | Moderate | 23 | |
| 56 | Moderate | 24 | |
| 53 | Moderate | 23 | |
| 57 | Moderate | 23 | |
| 58 | Moderate | 23 | |
| 62 | Moderate | 23 | |
| 69 | Moderate | 23 | |
| 60 | Moderate | 23 | |
| 53 | Moderate | 26 | |
| 39 | Good | 6 — partial day |
Questions about Stockton
What is the air quality in Stockton right now?
Which monitor does this number come from?
How does Stockton compare with metros nearby?
Does this include pollen?
Put this number in context
Updated