Air Quality in Longmont, United States

Rain
29.5°C · 24.9% humidity
29.5°
Feels 29.5°
23
Good
Air quality is satisfactory. Enjoy outdoor activities.
6 stations

Nearby Monitoring Stations

AQI Forecast Calibrated
23 12pm
21
21
23 3pm
21
21
21 6pm
21
21
23 9pm
23
23
23 12am
23
23
21 3am
21
21
21 6am
21
21
21 9am
21
21
Station readings
23
9
CAMS model adj -4
27
25
25
25
25
25
25
25
25
27
27
27
27
27
27
25
25
25
25
25
25
25
25
25
AD 728×90

Air Quality Index Trend

11h · 1 stn

Longmont's air quality is primarily affected by vehicle emissions and industrial activity. Seasonal wildfire smoke and weather patterns can cause periodic air quality deterioration. Current PM2.5 concentration in Longmont is 1.1× the WHO annual guideline of 5 µg/m³.

24.9%
Humidity
67.6 km/h
Wind W
1010.9 hPa
Pressure
5.9
UV High
GoodModerateUSGUnhealthyVery UnhealthyHazardous

Which pollutant is driving the AQI?

PM2.5▲
23
5.39 µg/m³
PM10
13
13.7 µg/m³
050100150200300500

What is the weather forecast for Longmont?

Temperature & Precipitation

PM2.5 Trend

11h · 1 station
PM2.55.39 µg/m³ ✓ WHO
Good
PM1013.7 µg/m³
Good
UV INDEX5.9
High
AD 300×250
Station readings (6 stations within 25 km)
5.39
Median
4.64
Average
3.0
Low
6.38
High
PM2.5 µg/m³ · Model: 6.25 · Bias: +0.9

What is the 7-day forecast for Longmont?

05-28
31.2° 10.0°
6.25 mm
05-29
31.6° 13.9°
7.94 mm
05-30
30.0° 12.6°
0.25 mm
05-31
29.2° 14.2°
0.94 mm
06-01
28.1° 13.6°
06-02
34.8° 15.9°
06-03
34.1° 13.7°
Both models agree Avg diff: 4.6°C

Where are air quality stations near Longmont?

27
Longmont Collocation 1
0.3 km PM2.5: 6.4 µg/m³
23
Longmont - Municipal, Colorado, USA
0.3 km PM2.5: 5.5 µg/m³
–
united-states-of-america-boulder-joslyn-court
20.4 km
27
Athens, Boulder-CU, Colorado, USA
22.2 km PM2.5: 6.5 µg/m³
12
Platteville Middle School
24.1 km PM2.5: 3.0 µg/m³
30
Silver Creek
25.2 km PM2.5: 7.2 µg/m³
21
Anythink Brighton Library
31.3 km PM2.5: 5.0 µg/m³

What cities are near Longmont?

24 Erie 23 Louisville 21 Boulder 23 Loveland 25 Broomfield 25 Northglenn 22 Thornton 23 Sherrelwood 23 Arvada 9 Evans
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Data sources: AQI from ground-level monitoring stations via AQICN. Weather forecast from ECMWF (IFS & CAMS models). AQI calculated using US EPA standard. Updated 2026-05-28T21:46 UTC.