Cupertino, California Air Quality
Cupertino has a median AQI of 47, earning an air quality grade of B+ — good air quality that ranks better than 22% of US cities. Air quality has remained relatively stable over the past decade. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2024, Cupertino recorded 201 good air quality days (55% of monitored days) and 1 unhealthy days.
Population: 58,566 • County: Santa Clara
Current AQI
Quick Facts
| Current AQI | 57 — Moderate |
| Air Quality Grade | B+ |
| Median AQI (2024) | 47 |
| vs. U.S. Cities | Better than 22% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 1 |
| 10-Year Trend | → Stable |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is acceptable. However, there may be a risk for some people who are unusually sensitive to air pollution.
Unusually sensitive people should consider reducing prolonged or heavy outdoor exertion.
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Cupertino is sourced from the San Jose - Jackson St. monitoring area, located approximately 9 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
Wildfire smoke is a significant factor in Cupertino's air quality, with regional fires capable of pushing AQI from Good to Unhealthy within hours during fire season (typically July through October). On smoke-impacted days, staying indoors with windows closed and running an air purifier with a HEPA filter is the most effective protection.
AQI Trend (10 Years)
Air Quality Days by Year
Cupertino Median AQI by Year
Annual EPA air quality data for Cupertino — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2024 | 47 | 201 | 1 | 111 | PM2.5 |
| 2023 | 43 | 240 | 4 | 134 | Ozone |
| 2022 | 49 | 188 | 5 | 119 | PM2.5 |
| 2021 | 53 | 147 | 7 | 147 | PM2.5 |
| 2020 | 52 | 174 | 20 | 198 | PM2.5 |
| 2019 | 48 | 205 | 4 | 136 | PM2.5 |
| 2018 | 53 | 154 | 17 | 214 | PM2.5 |
| 2017 | 52 | 174 | 12 | 182 | PM2.5 |
| 2016 | 50 | 187 | 1 | 101 | PM2.5 |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2024 Air Quality Summary
Primary Pollutant Days (2024)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Cupertino Air Quality
What is the air quality in Cupertino today?
The current AQI in Cupertino is 57, rated "Moderate". Air quality is moderate — unusually sensitive individuals may want to limit prolonged outdoor exertion. Air quality is acceptable. However, there may be a risk for some people who are unusually sensitive to air pollution.
Is air quality in Cupertino getting better or worse?
Air quality in Cupertino has been stable. The median AQI has dropped 3 points (from 50 in 2016 to 47 in 2024).
What is the most common air pollutant in Cupertino?
PM2.5 is the primary air pollutant in Cupertino, responsible for 334 days (92% of monitored days) in 2024. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does Cupertino have per year?
In 2024, Cupertino recorded 55% good air quality days (201 days) out of 363 monitored days. There were 1 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 111.
What air quality grade does Cupertino receive?
Cupertino receives an air quality grade of B+, placing it better than 22% of US cities. This is based on a median AQI of 47 in 2024, with 201 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 22% of US cities
Nearby Cities
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National Rankings
See how Cupertino compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Cupertino
Cupertino faces elevated PM2.5 from wildfire smoke in addition to year-round traffic and industrial sources. We prioritize True HEPA units with high smoke CADR — essential for rapid air cleaning during smoke events.
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