Today | Weather | Wednesday, May 20, 2026

Weather in Thornton, Colorado

02:50 PM
Now
Cloudy Weather
57° F
Feels Like 64°
Precipitation 54 %
Wind 6 mph
UV Index (0 - 11+) 4
Humidity 57 %
Today
Sunny with a Chance of Thunderstorms
Day 61°
Night 41°
Precipitation 88 %
Wind 7 mph
UV Index (0 - 11+) 4

Thornton Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (May 20, 2025)
Partly Sunny with Showers

Day

70°

Night

45°

Wind

12 mph

UV Index

11

Precipitation

49 %

Air Quality in Thornton

NOW
40 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 0.77 µg/m³
PM10 1.33 µg/m³
O3 0.043 ppm
NO2 0.1 ppb
SO2 0.1 ppb
CO 0.08 ppm
NH3 0.54 µg/m³
NO 0.03 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)
PM2.50.77 µg/m³
PM101.33 µg/m³
O384.96 µg/m³
NO20.15 µg/m³
SO20.16 µg/m³
CO92.18 µg/m³
NH30.54 µg/m³
NO0.03 µg/m³