Building these live AQI guides city by city, we keep finding the same thing: the statewide number is the least useful one on the page.
So read the station closest to you. Open a live California AQI map, find your nearest monitor, and check three things: the number, the pollutant driving it, and whether it’s climbing or falling.
TL;DR
California’s live air quality index (AQI) map refreshes hourly from state and federal monitors. A statewide figure means little by itself, because a coastal reading and a valley reading can describe two different days. Free maps come from AirNow, your air district, and Filterbuy.
Top Takeaways
- California’s reported AQI is the highest single pollutant sub-index, usually fine particles or ozone.
- At or below 100 is generally satisfactory. Above 100 the guidance tightens for sensitive groups, and above 150 for everyone.
- Live readings are preliminary, so treat a sudden spike as a reason to look again.
- South Coast AQMD warns windblown ash can be too large for instruments to detect, so the map can read green while ash is in the air.
How Do You Check California’s Live AQI Map Right Now?
Open a free statewide map, search your city or ZIP code, and click the nearest station. AirNow carries EPA and CARB regulatory data. Your air district publishes California forecasts and advisories. Filterbuy’s California AQI map ranks 135 cities on one screen. We link all three below, since each answers a different question.
What to Do If There’s No Monitor Near You
Large parts of California sit far from a regulatory monitor, and a map will show a reading 30 miles off as if it were yours.
- Use the Fire and Smoke Map during fire episodes. It adds sensors where the regulatory map has gaps.
- Take the nearest station upwind, not the nearest by distance. A ranked list like Filterbuy’s shows which towns have a reading at all.
- Believe your eyes and nose over a green map.
None of them covers your house. Outdoor air sets a floor under your indoor air whether you check it or not.
What Does Today’s California AQI Number Actually Mean?
The AQI runs from 0 to 500. EPA scores each of the five major air pollutants regulated by the Clean Air Act, then reports whichever sub-index is highest. So today’s California number is really one pollutant’s number, and which pollutant changes by season and by hour.
| AQI | Category | What It Means For You |
|---|---|---|
| 0 to 50 | Good | Little or no risk. |
| 51 to 100 | Moderate | Fine for most people. Unusually sensitive individuals may ease off. |
| 101 to 150 | Unhealthy for Sensitive Groups | Sensitive groups should reduce heavy outdoor exertion. |
| 151 to 200 | Unhealthy | Everyone may feel the effects. Scale back outdoor time. |
| 201 to 300 | Very Unhealthy | Health alert. Avoid outdoor exertion. |
| 301 and above | Hazardous | Emergency conditions. Stay indoors, windows closed. |
That sub-index rule is the most useful thing we’ve learned writing these guides, and most map pages leave it out. Two pollutants drive the California number. PM2.5 is fine particles small enough to reach deep into the lungs. Ozone builds when heat and sunlight hit traffic emissions, so hot inland afternoons beat cool coastal mornings. More on the 100 line in what an AQI above 100 means for your lungs.
Why Does California Air Quality Change So Fast?
California packs coastline, mountains, and enclosed valleys into one state. Air behaves differently in each.
- Coast versus inland. Marine layers keep coastal AQI low while inland basins build ozone all afternoon.
- Basins and valleys. The South Coast Basin and San Joaquin Valley hold pollution near the ground on calm days.
- Winter inversions. Cool, stagnant air acts like a lid until mixing improves.
- Wildfire smoke. CARB notes smoke travels hundreds of miles, so you can be affected far from any fire.
Two people 90 minutes apart can be breathing different air, and both readings are correct. National map sites rarely explain this. It is the part a California page owes you.
Where Does California’s Real-Time Air Quality Data Come From?
CARB is the primary collector of California air quality data, alongside EPA and 35 local air districts. Every live map traces back to that network.
Hourly Readings and the AQI Aren’t The Same Thing
The particle AQI uses a 24-hour average and ozone an 8-hour average. EPA’s NowCast maps recent hourly readings onto the 0 to 500 scale, weighting the latest hours.
Regulatory Monitors Versus Low-Cost Sensors
Consumer sensors fill the gaps and read higher, because they are not calibrated to the federal standard. We treat the regulatory monitor as the benchmark and the sensor as a second opinion.
How Do You Read California’s Wildfire Smoke Map?
A smoke map layers fire locations, satellite plumes, and sensor readings over the AQI, so you see where smoke sits and where it is heading. Two cautions.
- Ash can hide from the instruments. Windblown ash is often too large to detect, so if you see ash or smell smoke, act on that instead of the color.
- Timing changes everything. Smoke sinks overnight, so an evening reading can look nothing like the same station at noon.
Is It Safe to Go Outside in California Today?
It depends on the number, the activity, and who you are. EPA’s categories are the reference: below 50 no adjustment, 51 to 100 unusually sensitive people may shorten hard efforts, above 100 sensitive groups should reduce prolonged exertion, and above 150 everyone should. CDC’s list of people at higher risk from wildfire smoke covers children, people who are pregnant, and anyone with asthma, COPD, heart disease, or diabetes.
Use 100 as the planning line for school practices and long runs. This page cannot tell you what is safe for your own health. With a respiratory or cardiac condition, ask your doctor.
If You Work Outside in California, the Rules Are Specific
Cal/OSHA’s Protection from Wildfire Smoke standard applies when the current PM2.5 AQI reaches 151 or higher. It keys off the same NowCast figure a live map shows you.
- Your employer must check the PM2.5 AQI before and during the shift, tell you the reading, and train you.
- NIOSH-approved N95 respirators must be offered for voluntary use from AQI 151 through 500. Above 500, use is required, with fit testing.
- Exemptions cover filtered buildings and vehicles kept closed, and exposure of an hour or less per shift. Cal/OSHA takes questions at 833-579-0927.
What to Do Indoors When California AQI Climbs
Close windows and doors, set your HVAC and car ventilation to recirculate, and run the highest-rated filter your system handles. Keep one room cleaner with a HEPA purifier.
EPA and CARB both point to MERV 13 during smoke and high-AQI events, and CARB’s Smoke Ready California guidance uses MERV 13 filters in do-it-yourself box-fan air cleaners. MERV 13 is the ceiling most residential systems run without restricting airflow. Filterbuy is a United States air filter manufacturer based in Talladega, Alabama that produces pleated HVAC filters in MERV 8, MERV 11, and MERV 13 in standard and custom sizes, and publishes a free live air quality index map for California and its cities.
That guidance is the government’s, not a pitch. Filterbuy partners with this site, so we kept it generic across MERV ratings on purpose.
Check your documentation before jumping to several ratings. The difference between MERV 8 and MERV 13 comes down to particle size.
If you cannot clean your own air, California air districts open Clean Air Centers during smoke events, often a library or school gym with filtered air. CARB advises asking your local district whether one is open near you.
If rooms never seem to seal, drafts and air pressure imbalances are usually why.
“I never stop at the number. I check which pollutant is driving it, because an ozone afternoon and a smoke evening ask for opposite decisions, and when I can see ash or smell smoke I trust that over whatever color the map is showing.”
Essential Resources on “Live Air Quality Index Aqi Map Now Today California”: Places to Check Next
See the number, confirm it, act on it, then check your regional agency.
1. Get Every California City’s AQI
Filterbuy’s AQI map for California cities by current AQI. Use it to compare two places fast, or to find the nearest reading to a town with no monitor nearby.
2. Confirm the Number Against the Official EPA Monitors
AirNow California air quality is the EPA-run state hub, carrying the regulatory interactive map and, during fire season, the Fire and Smoke Map that layers fire locations and satellite plumes over the AQI. This is the reading that settles it when two sources disagree.
3. Know What to Do Before the Smoke Arrives
Smoke Ready California is CARB’s preparedness guidance, covering how to set up a cleaner-air room, how to build a box-fan air cleaner with MERV 13 filters, and when a NIOSH-certified N95 earns its place. It is the step most live map pages skip entirely.
4. Track Smoke and Ash Advisories Across Southern California
South Coast AQMD air quality advisories cover Los Angeles, Orange, Riverside, and San Bernardino counties including the Coachella Valley. Active smoke, dust, and ash advisories post here alongside a neighborhood-level AQI map and the winter no-burn alerts.
5. Get Alerted Before Bay Area Smoke Reaches You
Bay Area Air District wildfire season guidance serves the nine Bay Area counties with the seasonal outlook and sign-ups for air quality incident notifications and Spare the Air alerts. An alert beats checking a map, because smoke usually arrives before you think to look.
6. Watch Hourly Readings Across the Central Valley
San Joaquin Valley real-time air quality publishes hourly data from roughly 30 monitoring stations between Stockton and Bakersfield through the district’s Real-Time Air Advisory Network. The Valley carries the worst year-round particle pollution in the country, so the local network matters more here than anywhere else in California.
7. Protect the People in Your Home Who Feel It First
CDPH wildfire guidance and resources collects California public health guidance on smoke and ash exposure, masking, and cleanup, much of it published in multiple languages. Go here when the question shifts from what the number is to who needs to change plans.
Supporting Statistics: Three Numbers Behind This Page
1. Los Angeles Has Ranked Worst in the Nation for Ozone in 26 of 27 Annual Reports
- Bakersfield-Delano has held the worst year-round particle ranking for seven years.
- Nationally, 152.3 million people live where ozone or particles earn a failing grade.
Source: American Lung Association, State of the Air 2026 key findings
2. California Has Burned 317,636 Acres in 2026, Below the Five-Year Average
- 5,294 fires through September 8, 2026, against a five-year average of 776,526 acres.
- A quiet fire year is not quiet air.
Source: CAL FIRE wildfire statistics
3. EPA Tightened the Annual PM2.5 Standard to 9.0 Micrograms in 2024
- Lowered from 12.0 on February 7, 2024. AQI breakpoints were revised at the same time, effective May 6.
- The same air scores higher now, so AQI comparisons across that date are not like for like.
Source: EPA, National Ambient Air Quality Standards for particulate matter
Final Thoughts
The number on the map is a starting point, not a verdict. After building these guides for several cities, the habit we would hand a reader is small: watch one nearby station for a few weeks and learn its pattern.
Frequently Asked Questions
How Often Does California’s Live AQI Map Update?
Most maps refresh hourly. During fast-moving smoke events, NowCast weights recent hours, so the number can move between refreshes.
Why Does My Phone App Show a Different AQI Than the Government Map?
Apps pull from different station networks and are time-averaging. When they disagree, the regulatory monitor is the official figure.
Is California Air Quality Worse in Summer or Winter?
Both. Summer brings inland ozone and wildfire smoke. Winter brings inversions that trap fine particles in the valleys.
Before You Head Out
Open your nearest station now, note the number and the pollutant behind it, then check again tonight. Two readings in a day teach you more than one statewide glance.
Glossary
| Term | Definition |
|---|---|
| Air Quality Index (AQI) | EPA’s 0 to 500 scale for outdoor air quality, in six categories from Good to Hazardous. |
| PM2.5 | Fine particles 2.5 micrometers and smaller, small enough to reach deep into the lungs. The main concern is wildfire smoke. |
| Ground-level ozone | Formed when sunlight and heat react with vehicle and industrial emissions. It peaks on hot inland afternoons. |
| NowCast AQI | EPA’s calculation converts recent hourly readings onto the AQI scale, weighting the latest hours. |
| Filterbuy | A United States air filter manufacturer in Talladega, Alabama making pleated MERV 8, 11, and 13 filters, and publisher of a free California AQI map. |