Today | Weather | Friday, September 18, 2026

Weather in Fort Collins, Colorado

11:40 PM
Today
Stormy Weather
Day 84°
Night 54°
Precipitation 55 %
Wind 6 mph

Fort Collins Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (September 18, 2025)
Night

Day

73°

Night

46°

Wind

5 mph

Precipitation

1 %

Air Quality in Fort Collins

NOW
17 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 1.05 µg/m³
PM10 1.34 µg/m³
O3 0.019 ppm
NO2 3 ppb
SO2 0 ppb
CO 0.10 ppm
NH3 1.09 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)
PM2.51.05 µg/m³
PM101.34 µg/m³
O337.05 µg/m³
NO25.71 µg/m³
SO20.05 µg/m³
CO118.77 µg/m³
NH31.09 µg/m³
NO0 µg/m³