SmogRank / United States / Watsonville

Watsonville, month by month

Watsonville has a measured daily mean on 470 days since 16 May 2024. Its worst month was December 2024, at 51 US AQI (9.2 µg/m³), 1,021st of 2,616 cities on that month's world ranking. Its cleanest was September 2026, at 29 US AQI (5.2 µg/m³).

Every month since 2024

2026too few days for a mean (a year needs 199)104 days measured
Jan44#1,495Feb15 daysMar16 daysApr1 dayMay3 daysJun2 daysJul5 daysAug12 daysSep29Oct6 days
2025too few days for a mean (a year needs 256)186 days measured
Jan16 daysFeb14 daysMar18 daysApr13 daysMay3 daysJun4 daysJul18 daysAug33#2,510Sep34#2,012Oct14 daysNov20 daysDec17 days
2024too few days for a mean (a year needs 257)180 days measured
JanFebMarAprMay13 daysJun32#2,080Jul34#1,925Aug16 daysSep14 daysOct33#1,526Nov36#1,874Dec51#1,021
Each square is a month's mean PM2.5 in US AQI from Watsonville'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 Watsonville 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

21 months
MonthWhy
Oct 20266 of 11 days measured; a month needs 8. The others: 5 with under 18 hours of readings or readings that failed our checks.
Aug 202612 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks.
Jul 20265 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Jun 20262 of 30 days measured; a month needs 21. The others: 28 with under 18 hours of readings or readings that failed our checks.
May 20263 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Apr 20261 of 30 days measured; a month needs 21. The others: 29 with under 18 hours of readings or readings that failed our checks.
Mar 202616 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
Feb 202615 of 28 days measured; a month needs 20. The others: 13 with under 18 hours of readings or readings that failed our checks.
Dec 202517 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks.
Nov 202520 of 30 days measured; a month needs 21. The others: 10 with under 18 hours of readings or readings that failed our checks.
Oct 202514 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks.
Jul 202518 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks.
Jun 20254 of 30 days measured; a month needs 21. The others: 26 with under 18 hours of readings or readings that failed our checks.
May 20253 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Apr 202513 of 30 days measured; a month needs 21. The others: 17 with under 18 hours of readings or readings that failed our checks.
Mar 202518 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks.
Feb 202514 of 28 days measured; a month needs 20. The others: 14 with under 18 hours of readings or readings that failed our checks.
Jan 202516 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
Sep 202414 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks.
Aug 202416 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
May 202413 of 31 days measured; a month needs 22. The others: 3 with under 18 hours of readings or readings that failed our checks.

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

Watsonville's worst months

MonthUS AQIDays measuredWorld rank
December 2024 519.2 µg/m³31 of 311,021stof 2,616
January 2026 448.0 µg/m³23 of 311,495thof 2,617
November 2024 366.4 µg/m³30 of 301,874thof 2,624
July 2024 346.2 µg/m³22 of 311,925thof 2,566
September 2025 346.2 µg/m³25 of 302,012thof 3,104
August 2025 336.0 µg/m³24 of 312,510thof 2,901

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.

Watsonville's worst days

DayUS AQI
8 Dec 2024 7924.1 µg/m³
28 Nov 2025 7220.2 µg/m³
11 Dec 2024 6818.4 µg/m³
10 Dec 2024 6818.2 µg/m³
18 Jan 2025 6717.7 µg/m³
14 Dec 2025 6616.9 µg/m³
5 Dec 2024 6516.4 µg/m³
29 Nov 2025 6416.2 µg/m³
19 Jan 2025 6416.1 µg/m³
7 Dec 2025 6416.1 µg/m³

Daily means, the highest since 16 May 2024; 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, Watsonville, United States, 16 May 2024 – 10 Oct 2026. Monitor data from national networks via OpenAQ and the publishers listed at smogrank.com/sources. smogrank.com/us/watsonville/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.

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

Updated 2026-10-12 18:07 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).