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Active Weather Warnings

Dense Fog Advisory

Weather in Decatur, Illinois

01:12 AM

Now

45° F

Feels Like 43°

Precipitation 0 %

Wind 5 mph

Humidity 89 %

Today

Day 61°

Night 43°

Precipitation 11 %

Wind 12 mph

UV Index (0 - 11+) 2

Decatur Weather Forecast Updated

Last updated on December 25, 2025 at 11:45 PM

Air Quality in Decatur

NOW

29 AQI

Good air quality Dominant pollutant: O₃

Pollutant Concentrations:

PM_2.5 6.65 µg/m³

PM₁₀ 8.27 µg/m³

O₃ 0.031 ppm

NO₂ 2.2 ppb

SO₂ 0.5 ppb

CO 0.14 ppm

NH₃ 0.08 µg/m³

NO 0 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 – 6.65 µg/m³

PM₁₀ – 8.27 µg/m³

O₃ – 60.63 µg/m³

NO₂ – 4.22 µg/m³

SO₂ – 1.23 µg/m³

CO – 161.78 µg/m³

NH₃ – 0.08 µg/m³

NO – 0 µg/m³

View Hourly Air Quality Forecast

Weather Alerts and Warnings for Decatur

Moderate Expected Likely

Dense Fog Advisory

Dense Fog Advisory issued December 25 at 11:18PM CST until December 26 at 4:00AM CST by NWS Lincoln IL

Dec 25, 11:18 PM → Dec 26, 4:00 AM

WHAT: Visibility one quarter mile or less in dense fog.

WHERE: Portions of central, east central, southeast, and west
central Illinois.

WHEN: Until 4 AM CST Friday.

IMPACTS: Low visibility could make driving conditions hazardous.

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If driving, slow down, use your headlights, and leave plenty of distance ahead of you.

Updated: Dec 25, 11:45 PM Source: NWS Alert