What is the air quality trend in Longmont?

Over the past 8 days, Longmont had an average AQI of 68 based on station measurements. The worst day was 2026-08-04 with AQI 86.

How is Longmont air quality measured?

Air quality in Longmont is measured by ground-level monitoring stations that report PM2.5 and PM10 concentrations hourly. CERNS.IO aggregates readings from nearby stations and converts PM2.5 to the US EPA Air Quality Index (AQI) scale.

Air Quality History for Longmont, United States

Name: Longmont Air Quality History
Creator: CERNS.IO
License: https://creativecommons.org/licenses/by/4.0/

Historical PM2.5 and AQI trend from monitoring stations near Longmont, United States.

Current AQI
Good CAMS model

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

165h

PM2.5 Station

165h · 33 stations

Temperature GFS model

28pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	PM10 avg	Hours	Stations
2026-08-08	77	77–77	24.6 µg/m³	40.4	1h	33
2026-08-07	75	70–80	23.7 µg/m³	46.0	24h	31
2026-08-06	71	66–75	21.5 µg/m³	51.9	24h	30
2026-08-05	73	66–88	22.7 µg/m³	42.7	24h	31
2026-08-04	86	77–98	28.7 µg/m³	56.6	24h	29
2026-08-03	62	34–80	17.9 µg/m³	48.3	24h	27
2026-08-02	45	39–51	10.9 µg/m³	18.2	24h	26
2026-08-01	55	45–60	14.0 µg/m³	25.8	20h	27

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