Today | Weather | Thursday, May 21, 2026

Weather in Fort Collins, Colorado

12:15 AM
Now
Cloudy Night
48° F
Feels Like 46°
Precipitation 32 %
Wind 6 mph
Humidity 82 %
Today
Sunny with a Chance of Thunderstorms
Day 66°
Night 39°
Precipitation 55 %
Wind 7 mph
UV Index (0 - 11+) 11

Warning: Extreme UV Index Today: 11

Overexposure to the sun's harmful UV rays can cause sunburn and increase the risk of developing skin cancer, including melanoma. Protect yourself by wearing clothing that covers your skin, sunglasses, and a hat. Apply a broad-spectrum sunscreen with an SPF of 30 or higher every two hours, even on cloudy days. Minimize direct sun exposure during peak hours (10 AM to 4 PM) to reduce the risk.

Fort Collins Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (May 21, 2025)
Sunny Weather

Day

75°

Night

41°

Wind

12 mph

UV Index

11

Precipitation

25 %

Air Quality in Fort Collins

NOW
42 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 2.16 µg/m³
PM10 2.86 µg/m³
O3 0.046 ppm
NO2 2.1 ppb
SO2 0.1 ppb
CO 0.10 ppm
NH3 3.41 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)
PM2.52.16 µg/m³
PM102.86 µg/m³
O389.97 µg/m³
NO23.9 µg/m³
SO20.36 µg/m³
CO110.82 µg/m³
NH33.41 µg/m³
NO0 µg/m³