Today | Weather | Tuesday, June 9, 2026

Active Weather Warnings

Weather in Thornton, Colorado

05:48 PM

Now

86° F

Feels Like 82°

Precipitation 40 %

Wind 13 mph

UV Index (0 - 11+) 1

Humidity 18 %

Today

Day 88°

Night 59°

Precipitation 40 %

Wind 9 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.

Thornton Weather Forecast Updated

8 minutes ago

Last updated on June 09, 2026 at 5:40 PM

Weather Forecast History

Last Year's Weather on This Day (June 9, 2025)

Day

81°

Night

55°

Wind

6 mph

UV Index

Precipitation

25 %

Air Quality in Thornton

NOW

42 AQI

Good air quality Dominant pollutant: O₃

Pollutant Concentrations:

PM_2.5 1.49 µg/m³

PM₁₀ 2.82 µg/m³

O₃ 0.045 ppm

NO₂ 0.1 ppb

SO₂ 0.1 ppb

CO 0.06 ppm

NH₃ 0.48 µg/m³

NO 0.03 µg/m³

PM_2.5 – 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)

PM_2.5 – 1.49 µg/m³

PM₁₀ – 2.82 µg/m³

O₃ – 88.74 µg/m³

NO₂ – 0.23 µg/m³

SO₂ – 0.32 µg/m³

CO – 72.74 µg/m³

NH₃ – 0.48 µg/m³

NO – 0.03 µg/m³

View Hourly Air Quality Forecast

Weather Alerts and Warnings for Thornton

Severe Future Possible

Fire Weather Watch

Fire Weather Watch issued June 8 at 2:32AM MDT until June 9 at 9:00PM MDT by NWS Denver CO

Jun 9, 12:00 PM → Jun 9, 9:00 PM

* AFFECTED AREA...Fire Weather Zones 238, 239, 240, 241, 242,
243, 244, 245, 246, 247, 248, 249, 250 and 251.

* TIMING...From Tuesday afternoon through Tuesday evening.

* WINDS...Southwest 20 to 30 mph with gusts up to 40 mph.

* RELATIVE HUMIDITY...As low as 8 percent.

IMPACTS: Conditions will be favorable for rapid fire spread.
Avoid outdoor burning and any activity that may produce a
spark and start a wildfire.

+ Read More

A Fire Weather Watch means that critical fire weather conditions are forecast to occur. Listen for later forecasts and possible Red Flag Warnings.

Updated: Jun 8, 12:48 PM Source: NWS Alert

Severe Expected Likely

Red Flag Warning

Red Flag Warning issued June 9 at 12:57PM MDT until June 9 at 9:00PM MDT by NWS Denver CO

Jun 9, 12:57 PM → Jun 9, 9:00 PM

The National Weather Service in Denver has issued a Red Flag
Warning for wind and low relative humidity, which is in effect
from noon to 8 PM MDT Wednesday. The Fire Weather Watch is no
longer in effect.

* AFFECTED AREA...Fire Weather Zones 240, 241, 242, 243, 244,
245, 248, 250 and 251.

* TIMING...For the first Red Flag Warning, until 9 PM MDT this
evening. For the second Red Flag Warning, from noon to 8 PM
MDT Wednesday.

* WINDS...West 15 to 25 mph with gusts up to 40 mph.

* RELATIVE HUMIDITY...As low as 11 percent.

IMPACTS: Conditions will be favorable for rapid fire spread.
Avoid outdoor burning and any activity that may produce a
spark and start a wildfire.