SmogRank / United States / Arizona / Flagstaff

Flagstaff, month by month

Flagstaff has a measured daily mean on 391 days since 8 April 2025. Its worst month was July 2026, at 58 US AQI (12.9 µg/m³), 739th of 2,784 cities on that month's world ranking. Its cleanest was September 2026, at 27 US AQI (4.8 µg/m³).

Every month since 2025

2026too few days for a mean (a year needs 199)176 days measured
Jan10 daysFeb7 daysMar5 daysApr7 daysMay19 daysJun56#478Jul58#739Aug38#2,174Sep27#2,432Oct37#1,465
2025too few days for a mean (a year needs 256)215 days measured
JanFebMarApr31#2,417May32#2,014Jun33#2,174Jul39#1,982Aug38#2,249Sep32#2,193Oct37#1,281Nov6 daysDec14 days
Each square is a month's mean PM2.5 in US AQI from Flagstaff'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 Flagstaff 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

7 months
MonthWhy
May 202619 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Apr 20267 of 30 days measured; a month needs 21. The others: 23 with under 18 hours of readings or readings that failed our checks.
Mar 20265 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Feb 20267 of 28 days measured; a month needs 20. The others: 21 with under 18 hours of readings or readings that failed our checks.
Jan 202610 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Dec 202514 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks.
Nov 20256 of 30 days measured; a month needs 21. The others: 24 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.

Flagstaff's worst months

MonthUS AQIDays measuredWorld rank
July 2026 5812.9 µg/m³28 of 31739thof 2,784
June 2026 5612.0 µg/m³30 of 30478thof 2,497
July 2025 397.1 µg/m³31 of 311,982ndof 2,889
August 2025 386.8 µg/m³30 of 312,249thof 2,901
August 2026 386.8 µg/m³31 of 312,174thof 2,896
October 2025 376.7 µg/m³26 of 311,281stof 2,614

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.

Flagstaff's worst days

DayUS AQI
28 Jun 2026 17893.6 µg/m³
11 Nov 2025 16677.3 µg/m³
6 Nov 2025 15561.6 µg/m³
3 Jul 2026 14954.8 µg/m³
1 Jul 2026 12645.5 µg/m³
29 Jul 2026 12444.7 µg/m³
29 Jun 2026 11340.5 µg/m³
30 Jun 2026 10938.8 µg/m³
27 Jun 2026 10838.4 µg/m³
29 Oct 2025 9532.5 µg/m³

Daily means, the highest since 8 Apr 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, Flagstaff, United States, 8 Apr 2025 – 9 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/flagstaff/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.

Flagstaff 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).