What Is the Air Quality in Siskiyou, California?

Siskiyou, California earns a D — air quality falls below the U.S. average, with a 5-year median AQI of 41. Residents with asthma, COPD, heart disease, or young children should watch daily AQI forecasts and limit outdoor exertion when alerts go out.

Siskiyou, California's 5-year median AQI of 41 is right around the national average of 41 across the 1,020 monitored U.S. cities tracked here. Within California, Siskiyou, 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 Siskiyou, California has been getting worse over the past decade, with median AQI climbing by roughly 1.2 points per year. That bucks the national trend of broad improvement, and most often reflects either growing wildfire smoke exposure (particularly across the West) or rising local emissions from population and freight growth.

In 2014, Siskiyou, California posted a median AQI of 37. By 2023 that figure was 43 — a rise of 6 AQI points dirtier across 10 years of EPA records.

Across the past five years, this area has logged 82 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 16 days per year. That is roughly typical for a U.S. metro, with most caution days clustered in summer (ozone) or wildfire season.

Treat daily AQI forecasts as essential input. On flagged days, sensitive groups (asthma, COPD, heart disease, pregnancy, young children, older adults) should limit outdoor exertion and keep windows closed. A HEPA air cleaner sized to a bedroom or family room can cut indoor PM2.5 by 80%+ during smoke or pollution events. Because ozone peaks in the afternoon on hot sunny days, plan outdoor exercise for early morning or after sunset on bad-air days.