SmogRank / United States / California / Morro Bay

Morro Bay, month by month

Morro Bay has a measured daily mean on 50 days since 18 August 2026. Its worst month was September 2026, at 38 US AQI (6.8 µg/m³), 1,365th of 2,981 cities on that month's world ranking.

Every month since 2026

2026too few days for a mean (a year needs 199)50 days measured
JanFebMarAprMayJunJulAug14 daysSep38#1,365Oct6 days
Each square is a month's mean PM2.5 in US AQI from Morro Bay's measured days, with its place on that month's world ranking under it. A month has a mean once 70% of its days are measured, the rule the monthly rankings use; under that, the square gives the days measured. Each square opens that month's ranking with Morro Bay marked; each year, the year's.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

Months without a mean, and why

2 months
MonthWhy
Oct 20266 of 11 days measured; a month needs 8. The others: 4 with no readings from the monitor, 1 with readings for part of the day (a day needs 18 hours).
Aug 202614 of 31 days measured; a month needs 22.

A day counts once 18 hours of it are measured; a month needs 70% of its days.

Morro Bay's worst months

MonthUS AQIDays measuredWorld rank
September 2026 386.8 µg/m³30 of 301,365thof 2,981

Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.

Morro Bay's worst days

DayUS AQI
31 Aug 2026 8024.4 µg/m³
29 Aug 2026 6013.9 µg/m³
10 Sept 2026 5812.6 µg/m³
28 Aug 2026 5612.0 µg/m³
30 Aug 2026 5511.2 µg/m³
27 Aug 2026 5410.6 µg/m³
19 Aug 2026 5310.1 µg/m³
26 Aug 2026 529.6 µg/m³
13 Sept 2026 519.1 µg/m³
11 Sept 2026 498.9 µg/m³

Daily means, the highest since 18 Aug 2026; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.

Use this history

SmogRank, PM2.5 monthly and daily means, Morro Bay, United States, 18 Aug 2026 – 6 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/morro-bay/history (accessed 12 Oct 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.

Morro Bay now: the last 24 hours, its ranks today and the last 12 months day by day.

Updated 2026-10-12 21:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).