Today | Weather | Friday, November 21, 2025

Weather in Longmont, Colorado

06:28 PM
Now
Cloudy Night
45° F
Feels Like 43°
Precipitation 5 %
Wind 6 mph
Humidity 79 %
Today
Cloudy Weather
Day 48°
Night 30°
Precipitation 25 %
Wind 4 mph
UV Index (0 - 11+) 1

Longmont Weather Forecast Updated

53 minutes ago
Last updated on
Weather Forecast History
Last Year's Weather on This Day (November 21, 2024)
Cloudy Night

Day

52°

Night

30°

Wind

4 mph

Precipitation

1 %

Air Quality in Longmont

NOW
20 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 0.95 µg/m³
PM10 1.04 µg/m³
O3 0.021 ppm
NO2 4 ppb
SO2 0 ppb
CO 0.12 ppm
NH3 0.42 µg/m³
NO 0 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.50.95 µg/m³
PM101.04 µg/m³
O341.66 µg/m³
NO27.49 µg/m³
SO20.11 µg/m³
CO135.72 µg/m³
NH30.42 µg/m³
NO0 µg/m³