SmogRank / Czechia / South Moravian / Brno

Brno, month by month

Brno has a measured daily mean on 822 days since 1 January 2023. Its worst month was November 2024, at 67 US AQI (17.8 µg/m³), 293rd of 2,624 cities on that month's world ranking. Its cleanest was May 2024, at 39 US AQI (7.0 µg/m³).

Every month since 2023

2026too few days for a mean (a year needs 200)73 days measured
Jan11 daysFeb9 daysMar9 daysApr14 daysMay18 daysJun5 daysJulnoneAug1 daySep1 dayOct5 days
2025too few days for a mean (a year needs 256)171 days measured
Jan14 daysFeb19 daysMar11 daysApr10 daysMay12 daysJun3 daysJul10 daysAug52#1,278Sep19 daysOct10 daysNov16 daysDec58#861
2024too few days for a mean (a year needs 257)223 days measured
Jan65#390Feb58#427Mar15 daysApr46#1,281May39#1,692Jun1 dayJul46#1,233Aug1 daySepnoneOct10 daysNov67#293Dec66#370
202355 for the year355 days measured299th of 1,355 in the world
Jan58#317Feb62#334Mar58#127Apr54#338May52#527Jun52#841Jul46#825Aug51#750Sep54#439Oct53#349Nov51#798Dec65#242
Each square is a month's mean PM2.5 in US AQI from Brno'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 Brno 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

25 months
MonthWhy
Oct 20265 of 12 days measured; a month needs 9. The others: 6 with readings for part of the day (a day needs 18 hours), 1 with under 18 hours of readings or readings that failed our checks.
Sep 20261 of 30 days measured; a month needs 21. The others: 29 with readings for part of the day (a day needs 18 hours).
Aug 20261 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Jul 2026No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jun 20265 of 30 days measured; a month needs 21. The others: 25 with under 18 hours of readings or readings that failed our checks.
May 202618 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks.
Apr 202614 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks.
Mar 20269 of 31 days measured; a month needs 22. The others: 22 with under 18 hours of readings or readings that failed our checks.
Feb 20269 of 28 days measured; a month needs 20. The others: 19 with under 18 hours of readings or readings that failed our checks.
Jan 202611 of 31 days measured; a month needs 22. The others: 20 with under 18 hours of readings or readings that failed our checks.
Nov 202516 of 30 days measured; a month needs 21. The others: 14 with under 18 hours of readings or readings that failed our checks.
Oct 202510 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Sep 202519 of 30 days measured; a month needs 21. The others: 11 with under 18 hours of readings or readings that failed our checks.
Jul 202510 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Jun 20253 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
May 202512 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks.
Apr 202510 of 30 days measured; a month needs 21. The others: 20 with under 18 hours of readings or readings that failed our checks.
Mar 202511 of 31 days measured; a month needs 22. The others: 20 with under 18 hours of readings or readings that failed our checks.
Feb 202519 of 28 days measured; a month needs 20. The others: 9 with under 18 hours of readings or readings that failed our checks.
Jan 202514 of 31 days measured; a month needs 22. The others: 17 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 20241 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Jun 20241 of 30 days measured; a month needs 21. The others: 29 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.

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

Brno's worst months

MonthUS AQIDays measuredWorld rankEpisode
November 2024 6717.8 µg/m³27 of 30293rdof 2,624Eastern Europe, 25 to 29 November 2024
Europe, November 2024and 1 more
December 2024 6617.3 µg/m³24 of 31370thof 2,616Europe, 24 December 2024 to 3 January 2025
December 2023 6516.6 µg/m³31 of 31242ndof 2,247Eastern Europe, December 2023
Europe, December 2023and 1 more
January 2024 6516.4 µg/m³31 of 31390thof 2,385Europe, 27 January to 2 February 2024
Europe, 8 to 27 January 2024
February 2023 6215.1 µg/m³28 of 28334thof 1,129Europe, 28 February to 4 March 2023
Europe, 6 to 25 February 2023
March 2023 5813.0 µg/m³31 of 31127thof 911Europe, 28 February to 4 March 2023

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.

Brno's worst days

DayUS AQIEpisode
23 Jan 2026 15763.6 µg/m³Europe, January and February 2026
30 Dec 2024 14754.2 µg/m³Europe, 24 December 2024 to 3 January 2025
15 Jan 2026 14553.3 µg/m³Europe, January and February 2026
24 Jan 2026 13549.5 µg/m³Europe, January and February 2026
29 Dec 2024 12846.6 µg/m³Europe, 24 December 2024 to 3 January 2025
8 Nov 2024 12645.6 µg/m³Europe, November 2024
11 Feb 2025 12444.9 µg/m³Europe, 1 to 14 February 2025
22 Jan 2026 12344.3 µg/m³Europe, January and February 2026
9 Nov 2024 12143.6 µg/m³Europe, November 2024
23 Feb 2025 11541.2 µg/m³Europe, 14 February to 1 March 2025

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, Brno, Czechia, 1 Jan 2023 – 11 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/cz/brno/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.

Brno 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).