SmogRank / Slovenia / Urban Municipality of Koper / Koper
Koper, month by month
Koper has a measured daily mean on 790 days since 11 January 2023. Its worst month was February 2023, at 91 US AQI (30.4 µg/m³), 25th of 1,129 cities on that month's world ranking. Its cleanest was September 2026, at 23 US AQI (4.2 µg/m³).
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
Months without a mean, and why
19 months
| Month | Why |
|---|---|
| Jun 2026 | 14 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| May 2026 | 16 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks. |
| Oct 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2024 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2024 | 9 of 31 days measured; a month needs 22. The others: 22 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | 5 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks. |
| Feb 2024 | 1 of 29 days measured; a month needs 21. The others: 28 with under 18 hours of readings or readings that failed our checks. |
| Jan 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Dec 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Nov 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Oct 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2023 | 1 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Jun 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| May 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Apr 2023 | 3 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Jan 2023 | 7 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.
Koper's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| February 2023 | 9130.4 µg/m³ | 25thof 1,129 | Europe, 6 to 25 February 2023 |
| February 2025 | 7823.8 µg/m³ | 317thof 2,633 | Europe, 14 February to 1 March 2025 Europe, 1 to 14 February 2025 |
| November 2024 | 6617.0 µg/m³ | 330thof 2,624 | Eastern Europe, 25 to 29 November 2024 Southern Europe, November 2024and 1 more |
| January 2025 | 6617.0 µg/m³ | 397thof 2,474 | Germany, France and 19 more countries, January 2025 Europe, 24 December 2024 to 3 January 2025 |
| January 2026 | 6616.9 µg/m³ | 635thof 2,617 | Europe, January and February 2026 |
| December 2024 | 6013.7 µg/m³ | 542ndof 2,616 | Europe, 24 December 2024 to 3 January 2025 Serbia, Slovenia and 10 more countries, December 2024 |
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.
Koper's worst days
| Day | US AQI | Episode |
|---|---|---|
| 24 Feb 2025 | 17387.2 µg/m³ | Europe, 14 February to 1 March 2025 |
| 23 Feb 2025 | 16373.3 µg/m³ | Europe, 14 February to 1 March 2025 |
| 2 Feb 2023 | 16271.1 µg/m³ | – |
| 14 Nov 2025 | 16067.8 µg/m³ | Southern Europe, November 2025 |
| 1 Jan 2025 | 15865.2 µg/m³ | Europe, 24 December 2024 to 3 January 2025 |
| 22 Feb 2025 | 15764.7 µg/m³ | Europe, 14 February to 1 March 2025 |
| 2 Jan 2025 | 15560.5 µg/m³ | Europe, 24 December 2024 to 3 January 2025 |
| 18 Feb 2023 | 15358.4 µg/m³ | Europe, 6 to 25 February 2023 |
| 16 Jan 2026 | 15257.5 µg/m³ | Europe, January and February 2026 |
| 19 Feb 2023 | 14854.6 µg/m³ | Europe, 6 to 25 February 2023 |
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, Koper, Slovenia, 11 Jan 2023 – 11 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/si/koper/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.
Koper 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).