SmogRank / Ireland / Ulster / Letterkenny

Letterkenny, month by month

Letterkenny has a measured daily mean on 257 days since 22 May 2025. Its worst month was April 2026, at 37 US AQI (6.7 µg/m³), 1,984th of 2,941 cities on that month's world ranking. Its cleanest was July 2026, at 26 US AQI (4.7 µg/m³).

Every month since 2025

2026too few days for a mean (a year needs 199)180 days measured
Jan5 daysFeb1 dayMar4 daysApr37#1,984May32#2,069Jun20 daysJul26#2,635Aug31#2,606Sep35#1,585Oct36#1,546
2025too few days for a mean (a year needs 256)77 days measured
JanFebMarAprMay8 daysJun13 daysJul14 daysAug37#2,326Sep13 daysOct5 daysNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Letterkenny'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 Letterkenny marked; each year, the year's. A dashed square is the running month, so far.
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

11 months
MonthWhy
Jun 202620 of 30 days measured; a month needs 21. The others: 10 with under 18 hours of readings or readings that failed our checks.
Mar 20264 of 31 days measured; a month needs 22. The others: 27 with under 18 hours of readings or readings that failed our checks.
Feb 20261 of 28 days measured; a month needs 20. The others: 27 with under 18 hours of readings or readings that failed our checks.
Jan 20265 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Dec 2025No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2025No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 20255 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Sep 202513 of 30 days measured; a month needs 21. The others: 17 with under 18 hours of readings or readings that failed our checks.
Jul 202514 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks.
Jun 202513 of 30 days measured; a month needs 21. The others: 17 with under 18 hours of readings or readings that failed our checks.
May 20258 of 31 days measured; a month needs 22. The others: 2 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.

Letterkenny's worst months

MonthUS AQIDays measuredWorld rank
April 2026 376.7 µg/m³29 of 301,984thof 2,941
August 2025 376.6 µg/m³24 of 312,326thof 2,901
September 2026 356.3 µg/m³26 of 301,585thof 2,981
May 2026 325.7 µg/m³29 of 312,069thof 2,874
August 2026 315.6 µg/m³27 of 312,606thof 2,896
July 2026 264.7 µg/m³30 of 312,635thof 2,784

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.

Letterkenny's worst days

DayUS AQI
11 Sept 2026 6818.2 µg/m³
13 Aug 2025 6315.7 µg/m³
27 Aug 2026 6214.9 µg/m³
15 Jul 2026 6013.9 µg/m³
24 Apr 2026 5913.3 µg/m³
1 May 2026 5712.4 µg/m³
30 Mar 2026 5712.3 µg/m³
23 Apr 2026 5712.3 µg/m³
29 Mar 2026 5712.2 µg/m³
16 Jul 2026 5712.1 µg/m³

Daily means, the highest since 22 May 2025; 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, Letterkenny, Ireland, 22 May 2025 – 11 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/ie/letterkenny/history (accessed 12 Oct 2026).

Download chart (PNG)

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.

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

Updated 2026-10-12 20:07 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).