SmogRank / United States / California / Merced
Merced, month by month
Merced has a measured daily mean on 1,364 days since 1 January 2023. Its worst month was December 2024, at 72 US AQI (20.2 µg/m³), 259th of 2,616 cities on that month's world ranking. Its cleanest was March 2025, at 22 US AQI (4.0 µg/m³). 2025 averaged 44 US AQI (7.9 µg/m³), against 43 US AQI (7.8 µg/m³) in 2024.
Every month since 2023
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
Merced's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| December 2024 | 7220.2 µg/m³ | 259thof 2,616 | California and Oregon, United States, December 2024 |
| December 2023 | 6617.4 µg/m³ | 216thof 2,247 | Western United States and Mexico, December 2023 California and Oregon, United States, December 2023 |
| January 2025 | 6214.8 µg/m³ | 501stof 2,474 | – |
| January 2026 | 6114.2 µg/m³ | 800thof 2,617 | California, United States, 30 January to 6 February 2026 California and Oregon, United States, January 2026 |
| December 2025 | 6014.0 µg/m³ | 793rdof 3,006 | – |
| November 2023 | 5913.6 µg/m³ | 197thof 2,243 | – |
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.
Merced's worst days
Daily means, the highest since 1 Jan 2023; 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, Merced, United States, 1 Jan 2023 – 11 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/merced/history (accessed 12 Oct 2026).
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.
Merced now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 17:07 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).