SmogRank / Spain / Basque Country / Hernani

Hernani, month by month

Hernani has a measured daily mean on 647 days since 11 January 2023. Its worst month was February 2023, at 73 US AQI (20.7 µg/m³), 119th of 1,129 cities on that month's world ranking. Its cleanest was May 2024, at 34 US AQI (6.1 µg/m³).

Every month since 2023

2026too few days for a mean (a year needs 199)116 days measured
Jan21 daysFeb8 daysMarnoneAprnoneMay2 daysJun7 daysJul19 daysAug35#2,374Sep43#1,051Oct6 days
202542 for the year284 days measured1,887th of 2,681 in the world
Jan37#1,795Feb18 daysMar36#2,192Apr37#2,130May20 daysJun16 daysJul39#1,982Aug47#1,674Sep36#1,887Oct44#878Nov19 daysDec52#1,458
2024too few days for a mean (a year needs 257)192 days measured
Jan3 daysFeb51#797Mar15 daysApr37#1,504May34#1,978Jun10 daysJul12 daysAug7 daysSepnoneOct10 daysNov51#1,051Dec51#1,050
2023too few days for a mean (a year needs 256)55 days measured
Jan7 daysFeb73#119Mar20 daysApr3 daysMaynoneJunnoneJul1 dayAugnoneSepnoneOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Hernani'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 Hernani 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

30 months
MonthWhy
Oct 20266 of 11 days measured; a month needs 8. The others: 2 with no readings from the monitor, 3 with readings for part of the day (a day needs 18 hours).
Jul 202619 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Jun 20267 of 30 days measured; a month needs 21. The others: 23 with under 18 hours of readings or readings that failed our checks.
May 20262 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks.
Apr 2026No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Mar 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Feb 20268 of 28 days measured; a month needs 20. The others: 20 with under 18 hours of readings or readings that failed our checks.
Jan 202621 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks.
Nov 202519 of 30 days measured; a month needs 21. The others: 11 with under 18 hours of readings or readings that failed our checks.
Jun 202516 of 30 days measured; a month needs 21. The others: 14 with under 18 hours of readings or readings that failed our checks.
May 202520 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Feb 202518 of 28 days measured; a month needs 20. The others: 10 with under 18 hours of readings or readings that failed our checks.
Oct 202410 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Sep 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 20247 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks.
Jul 202412 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks.
Jun 202410 of 30 days measured; a month needs 21. The others: 20 with under 18 hours of readings or readings that failed our checks.
Mar 202415 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks.
Jan 20243 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Dec 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Sep 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 20231 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Jun 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
May 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Apr 20233 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Mar 202320 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Jan 20237 of 31 days measured; a month needs 22. The others: 14 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.

Hernani's worst months

MonthUS AQIDays measuredWorld rankEpisode
February 2023 7320.7 µg/m³24 of 28119thof 1,129Europe, 28 February to 4 March 2023
Europe, 6 to 25 February 2023and 1 more
December 2025 529.5 µg/m³30 of 311,458thof 3,006–
February 2024 519.2 µg/m³25 of 29797thof 2,486–
November 2024 519.1 µg/m³24 of 301,051stof 2,624–
December 2024 519.1 µg/m³26 of 311,050thof 2,616–
August 2025 478.4 µg/m³27 of 311,674thof 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.

Hernani's worst days

DayUS AQIEpisode
5 Mar 2023 10537.2 µg/m³Europe, 4 to 7 March 2023
18 Feb 2023 10236.0 µg/m³Europe, 6 to 25 February 2023
Spain, France and Portugal, February 2023
19 Feb 2023 9432.2 µg/m³Europe, 6 to 25 February 2023
Spain, France and Portugal, February 2023
20 Feb 2023 9432.2 µg/m³Europe, 6 to 25 February 2023
Spain, France and Portugal, February 2023
4 Mar 2023 9432.0 µg/m³Europe, 4 to 7 March 2023
Europe, 28 February to 4 March 2023
17 Feb 2023 8527.6 µg/m³Europe, 6 to 25 February 2023
Spain, France and Portugal, February 2023
4 Feb 2023 8326.5 µg/m³–
10 Feb 2023 8326.4 µg/m³Europe, 6 to 25 February 2023
2 Mar 2023 8225.6 µg/m³Europe, 28 February to 4 March 2023
3 Feb 2023 8125.3 µg/m³–

Daily means, the highest since 11 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, Hernani, Spain, 11 Jan 2023 – 9 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/es/hernani/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.

Hernani 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).