California · County air quality · 2025

Riverside County, California

Median AQI 80 (Moderate). 10.7% of monitored days rated Good, direct from EPA Air Quality System stations.

80
Median AQI
10.7%
Good-air days
34
Unhealthy days
0%
Cleaner than US counties

Riverside County's 2025 annual median AQI is 80 (Moderate), with 10.7% Good days

According to the U.S. EPA Air Quality System, Riverside County, California posted a 2025 median AQI of 80 (Moderate) across 365 monitored days, with 10.7% rated Good and 34 unhealthy or worse. This is an annual comparison, not today's advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US
Riverside County's 10.7% Good-day share places it cleaner than 0% of US counties in 2025.
Closest median-AQI peer
San Bernardino County (12.6% Good, median AQI 77) is the closest nationwide median-AQI peer to Riverside County.
2020–2025 trend
Riverside County's floor-qualifying Good-day share is improving from 2020 to 2025 (11.8% → 10.7%).
Median AQI
Median AQI: 80

According to the 2025 EPA AQS county release on PlainAirData, Riverside County, California ranks #951 of 951 by median AQI (80) and #949 by good-day share (10.7%). 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
  • Riverside County's Unhealthy-category days fell from 60 to 33 between the 2024 and 2025 EPA annual releases, a change of -27 days.
  • Riverside County's peak single-day AQI rose from 213 to 365 between the 2024 and 2025 EPA annual releases, a change of +152 points.
  • Riverside County's median AQI fell from 87 to 80 between the 2024 and 2025 EPA annual releases, a change of -7 points.
  • Riverside County's Good-day share fell from 11.7% to 10.7% between the 2024 and 2025 EPA annual releases, a change of -1.1 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

Riverside 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 Median AQI 80 0 50 100 150 200 300 500 Riverside County
  • Good · 39 d · 10.7%
  • Moderate · 217 d · 59.5%
  • USG · 75 d · 20.5%
  • Unhealthy · 33 d · 9.0%
  • Hazardous · 1 d · 0.3%

How did Riverside County's air break down in 2025?

Across 365 monitored days, 39 fell in the Good band (AQI 0–50) and 34 reached Unhealthy or worse. The worst single day peaked at AQI 365 (Hazardous).

EPA AQS →
Riverside County, Good days share 10.7%
National avg

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

Riverside County, Unhealthy-or-worse share 93.2%
National avg

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

Where Riverside County sits nationally

COUNT-derived placement among 951 US counties with at least 100 monitored days in 2025. Riverside County's Good-day share is 10.7% - cleaner than 0% of that comparison set.

Riverside County Good-day share vs. every US county

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

10.7% 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 Riverside County.

Riverside 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 · 56.7% PM2.5 · 33.2% 0% 25% 50% 75% 100% Riverside County, California · 365 monitored days Criteria pollutant column
  • Ozone · 207 days · 56.7%
  • PM2.5 · 121 days · 33.2%
  • PM10 · 37 days · 10.1%

2024 daily-monitor rhythm in Riverside 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 172, peak 213); Mar was cleanest at median 52. Summer months (Jun–Aug) averaged median AQI 145 vs 65 in Dec–Feb. 67 days crossed Unhealthy (AQI >150) at least once that year.

0 30 60 90 120 150 180 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 63 54 52 78 93 133 172 129 138 119 60 79
Riverside 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 (135), while Feb is lowest (56). Each cell is that month’s median daily AQI, not a current-air forecast.

JanFebMarAprMayJunJulAugSepOctNovDec
2020 695950641081211151191351057865
2021 56646191105131122136101668374
2022 6151628910812411511990705965
2023 54525395909015112699715864
2024 63545278931331721291381196079

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

Riverside County's air quality is rated Very Poor based on 10.7% good air days. There were 34 unhealthy days in 2025 when outdoor activity should be limited.

Air quality posed significant health risk in 2025. Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, pregnant women, and adults over 65, should monitor AirNow.gov alerts and limit outdoor activity on Unhealthy (AQI 151+) and Very Unhealthy (201+) days. Peak readings reached AQI 365, well into the Hazardous range.

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 207 of 365 monitored days.

5-Year Air Quality Trend

Air quality is improving in Riverside County. Highest Good-day share: 2023 (17.5%, 62 of 365 monitored days).

Year Good Moderate USG Unhealthy Median AQI
2020 42 179 98 36 87
2021 19 210 89 44 89
2022 41 198 86 31 77
2023 62 187 73 33 79
2024 43 176 80 60 87
2025 39 217 75 33 80

How does Riverside County compare?

How Riverside County compares

Good-day share worse than typical
Riverside County 10.7%
San Bernardino County, California 12.6%
Typical US county 76.0%
Median AQI worse than typical
Riverside County 80
San Bernardino County, California 77
Typical US county 39
Unhealthy days / yr worse than typical
Riverside County 34
San Bernardino County, California 43
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 Riverside 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.