SmogRank / United States / Montana / Missoula
Missoula, month by month
Missoula has a measured daily mean on 1,335 days since 1 January 2023. Its worst month was August 2026, at 70 US AQI (19.4 µg/m³), 256th of 2,896 cities on that month's world ranking. Its cleanest was June 2026, at 12 US AQI (2.2 µg/m³). 2025 averaged 27 US AQI (4.9 µg/m³), against 34 US AQI (6.2 µg/m³) in 2024.
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
Missoula's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| August 2026 | 7019.4 µg/m³ | 256thof 2,896 | North-western United States and Canada, 4 to 22 August 2026 North-western United States and Canada, July and August 2026 |
| September 2024 | 5812.6 µg/m³ | 252ndof 2,010 | North-western United States and Canada, 4 to 11 September 2024 North-western United States and Canada, 10 to 11 September 2024 |
| July 2026 | 5712.2 µg/m³ | 865thof 2,784 | North-western United States and Canada, July and August 2026 |
| July 2024 | 5712.1 µg/m³ | 417thof 2,566 | North-western United States and Canada, July 2024 |
| September 2025 | 5310.0 µg/m³ | 690thof 3,104 | North-western Canada and United States, September 2025 North-western United States and Canada, August and September 2025 |
| August 2023 | 519.3 µg/m³ | 734thof 1,980 | – |
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.
Missoula's worst days
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, Missoula, United States, 1 Jan 2023 – 10 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/missoula/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.
Missoula 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).