California · County air quality · 2025

San Bernardino County, California

Median AQI 77 (Moderate). 12.6% of monitored days rated Good, direct from EPA Air Quality System stations.

77
Median AQI
12.6%
Good-air days
43
Unhealthy days
0%
Cleaner than US counties

San Bernardino County's 2025 annual median AQI is 77 (Moderate), with 12.6% Good days

According to the U.S. EPA Air Quality System, San Bernardino County, California posted a 2025 median AQI of 77 (Moderate) across 365 monitored days, with 12.6% rated Good and 43 unhealthy or worse. This is an annual comparison, not today's advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US
San Bernardino County's 12.6% Good-day share places it cleaner than 0% of US counties in 2025.
Closest median-AQI peer
Los Angeles County (10.7% Good, median AQI 74) is the closest nationwide median-AQI peer to San Bernardino County.
2020–2025 trend
San Bernardino County's floor-qualifying Good-day share is improving from 2020 to 2025 (9.5% → 12.7%).
Median AQI
Median AQI: 77

According to the 2025 EPA AQS county release on PlainAirData, San Bernardino County, California ranks #950 of 951 by median AQI (77) and #947 by good-day share (12.6%). Ponce County, Puerto Rico is #1 of 951 by median AQI (3, 91.4% Good days) at good-day-share #159 ≠ largest of 7 at 100.0% Good days #1 by good-day share (100.0%, median AQI 9) at median-AQI #7.

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • San Bernardino County's peak single-day AQI fell from 593 to 207 between the 2024 and 2025 EPA annual releases, a change of -386 points.
  • San Bernardino County's Unhealthy-category days fell from 61 to 39 between the 2024 and 2025 EPA annual releases, a change of -22 days.
  • San Bernardino County's median AQI fell from 87 to 77 between the 2024 and 2025 EPA annual releases, a change of -10 points.
  • San Bernardino County's Good-day share rose from 10.9% to 12.6% between the 2024 and 2025 EPA annual releases, a change of +1.7 percentage points.

Compared against 366 monitored days in 2024 and 365 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Data updated August 2026

San Bernardino County AQI category distribution Stacked-segment bar showing the share of monitored days that fell in each EPA AQI category, Good, Moderate, USG, Unhealthy, Very Unhealthy, Hazardous, with median AQI marker. AQI category distribution 365 monitored days G M U X Median AQI 77 0 50 100 150 200 300 500 San Bernardino County
  • Good · 46 d · 12.6%
  • Moderate · 209 d · 57.3%
  • USG · 67 d · 18.4%
  • Unhealthy · 39 d · 10.7%
  • Very Unhealthy · 4 d · 1.1%

How did San Bernardino County's air break down in 2025?

Across 365 monitored days, 46 fell in the Good band (AQI 0–50) and 43 reached Unhealthy or worse. The worst single day peaked at AQI 207 (Very Unhealthy).

EPA AQS →
San Bernardino County, Good days share 12.6%
National avg

Share of monitored days at AQI 0-50 (Good band).

San Bernardino County, Unhealthy-or-worse share 100.0%
National avg

Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).

Where San Bernardino County sits nationally

COUNT-derived placement among 951 US counties with at least 100 monitored days in 2025. San Bernardino County's Good-day share is 12.6% - cleaner than 0% of that comparison set.

San Bernardino County Good-day share vs. every US county

Share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release

12.6% 0th percentile higher than 0% of 951 US counties

0.0%–5.0%: 0 US counties (0%). Below this entry. 5.0%–10.0%: 1 US counties (0%). Below this entry. 10.0%–15.0%: 4 US counties (0%). This entry sits in this band. 15.0%–20.0%: 4 US counties (0%). Above this entry. 20.0%–25.0%: 1 US counties (0%). Above this entry. 25.0%–30.0%: 5 US counties (1%). Above this entry. 30.0%–35.0%: 9 US counties (1%). Above this entry. 35.0%–40.0%: 4 US counties (0%). Above this entry. 40.0%–45.0%: 16 US counties (2%). Above this entry. 45.0%–50.0%: 16 US counties (2%). Above this entry. 50.0%–55.0%: 32 US counties (3%). Above this entry. 55.0%–60.0%: 50 US counties (5%). Above this entry. 60.0%–65.0%: 77 US counties (8%). Above this entry. 65.0%–70.0%: 93 US counties (10%). Above this entry. 70.0%–75.0%: 109 US counties (11%). Above this entry. 75.0%–80.0%: 114 US counties (12%). Above this entry. 80.0%–85.0%: 123 US counties (13%). Above this entry. 85.0%–90.0%: 99 US counties (10%). Above this entry. 90.0%–95.0%: 117 US counties (12%). Above this entry. 95.0%–100.0%: 70 US counties (7%). Above this entry. 100.0%–105.0%: 7 US counties (1%). Above this entry. This county 0.0% 100% every floor-qualified US county, bucketed by value

Each bar is a band; taller bars hold more US counties. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025

Pollutant Breakdown

Days where each pollutant was the primary driver of AQI readings in San Bernardino County.

San Bernardino County, California criteria pollutant distribution Stratified-band visualization showing the share of monitored days each criteria pollutant (PM2.5, PM10, O3, NO2, CO) was the primary AQI driver. Ozone · 61.6% PM2.5 · 34.2% 0% 25% 50% 75% 100% San Bernardino County, California · 365 monitored days Criteria pollutant column
  • Ozone · 225 days · 61.6%
  • PM2.5 · 125 days · 34.2%
  • PM10 · 11 days · 3.0%
  • NO₂ · 4 days · 1.1%

2024 daily-monitor rhythm in San Bernardino County

Month-by-month median AQI from EPA day-level county monitors (366 reported days in 2024). Jul posted the highest typical readings (median AQI 201, peak 227); Mar was cleanest at median 52. Summer months (Jun–Aug) averaged median AQI 170 vs 64 in Dec–Feb. 88 days crossed Unhealthy (AQI >150) at least once that year.

0 50 100 150 200 250 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 58 55 52 69 90 153 201 156 152 95 62 78
San Bernardino County median daily AQI by calendar month (2024, EPA daily county file)

Five-year seasonal record

EPA day-level county files · 2020–2024

1,827 daily readings show a recurring local pattern: Jul has the highest matched-month median AQI (173), while Mar is lowest (55). Each cell is that month’s median daily AQI, not a current-air forecast.

JanFebMarAprMayJunJulAugSepOctNovDec
2020 696554661261311611611631227563
2021 66716081112160156161119658372
2022 6960587911214515914792716163
2023 545452958095190143101636067
2024 5855526990153201156152956278

Lower AQI is better. The colors summarize EPA AQI bands; gaps mean the county had no day-level record for that month.

Health Impact Assessment

Very Poor

San Bernardino County's air quality is rated Very Poor based on 12.6% good air days. There were 43 unhealthy days in 2025 when outdoor activity should be limited.

Air quality reached unhealthy levels on 43 days in 2025 (39 Unhealthy, 4 Very Unhealthy). Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, and adults over 65, should review the daily breakdown below and follow local air-quality advisories on high-AQI days.

Sensitive group advisory

People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.

The dominant pollutant is Ozone, driving AQI on 225 of 365 monitored days.

5-Year Air Quality Trend

Air quality is improving in San Bernardino County. Highest Good-day share: 2023 (14.0%, 50 of 365 monitored days).

Year Good Moderate USG Unhealthy Median AQI
2020 33 170 76 69 93
2021 17 202 73 61 87
2022 23 212 67 56 77
2023 50 197 67 44 71
2024 40 182 56 61 87
2025 46 209 67 39 77

How does San Bernardino County compare?

How San Bernardino County compares

Good-day share worse than typical
San Bernardino County 12.6%
Los Angeles County, California 10.7%
Typical US county 76.0%
Median AQI worse than typical
San Bernardino County 77
Los Angeles County, California 74
Typical US county 39
Unhealthy days / yr worse than typical
San Bernardino County 43
Los Angeles County, California 32
Typical US county 1

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.

Informational only, not professional advice. Data from EPA AQS. See our disclaimer. Spotted a figure that looks wrong? Report a correction.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for San Bernardino County, California · 2020–2025

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Download this county's annual AQI row as CSV , with the same EPA fields and denominator shown on this page.

Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.