Hourly Weather Forecast for Decatur, Illinois

Hourly Weather | Today › Tuesday, September 1, 2026

Active Weather Warnings

Heat Advisory

Decatur, Illinois

11 AM

90°

Feels Like 97°

Humidity: 53%

UV Index: 5

Wind: 10 mph

12 PM

91°

Feels Like 100°

Humidity: 47%

UV Index: 6

Wind: 9 mph

1 PM

97°

Feels Like 104°

Humidity: 42%

UV Index: 7

Wind: 9 mph

2 PM

99°

Feels Like 104°

Humidity: 39%

UV Index: 6

Wind: 9 mph

3 PM

99°

Feels Like 106°

Humidity: 36%

UV Index: 5

Wind: 8 mph

4 PM

99°

Feels Like 102°

Humidity: 36%

UV Index: 4

Wind: 8 mph

5 PM

97°

Feels Like 100°

Humidity: 38%

UV Index: 2

Wind: 8 mph

6 PM

95°

Feels Like 99°

Humidity: 44%

UV Index: 1

Wind: 7 mph

7 PM

91°

Feels Like 97°

Humidity: 51%

UV Index: 0

Wind: 7 mph

8 PM

88°

Feels Like 93°

Humidity: 60%

UV Index: 0

Wind: 7 mph

9 PM

84°

Feels Like 90°

Humidity: 64%

UV Index: 0

Wind: 7 mph

10 PM

82°

Feels Like 86°

Humidity: 71%

UV Index: 0

Wind: 7 mph

11 PM

81°

Feels Like 84°

Humidity: 73%

UV Index: 0

Wind: 7 mph

Hourly Air Quality Forecast - AQI (US EPA)

11 AM

38 AQI

Good air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 9.05 µg/m³
PM₁₀: 9.93 µg/m³
O₃: 0.040 ppm
NO₂: 1.8 ppb
SO₂: 1.5 ppb
CO: 0.12 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

12 PM

45 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 10.19 µg/m³
PM₁₀: 11.07 µg/m³
O₃: 0.049 ppm
NO₂: 1.3 ppb
SO₂: 1.8 ppb
CO: 0.11 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

1 PM

56 AQI

Moderate air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 11.35 µg/m³
PM₁₀: 12.24 µg/m³
O₃: 0.056 ppm
NO₂: 1.1 ppb
SO₂: 1.9 ppb
CO: 0.11 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

2 PM

68 AQI

Moderate air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 10.89 µg/m³
PM₁₀: 11.66 µg/m³
O₃: 0.060 ppm
NO₂: 0.7 ppb
SO₂: 1.5 ppb
CO: 0.11 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

3 PM

67 AQI

Moderate air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 10.25 µg/m³
PM₁₀: 10.94 µg/m³
O₃: 0.059 ppm
NO₂: 0.6 ppb
SO₂: 1.2 ppb
CO: 0.10 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

4 PM

66 AQI

Moderate air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 10 µg/m³
PM₁₀: 10.68 µg/m³
O₃: 0.059 ppm
NO₂: 0.7 ppb
SO₂: 1.1 ppb
CO: 0.10 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

5 PM

52 AQI

Moderate air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 10.02 µg/m³
PM₁₀: 10.74 µg/m³
O₃: 0.055 ppm
NO₂: 1.3 ppb
SO₂: 1 ppb
CO: 0.10 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

6 PM

44 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 9.98 µg/m³
PM₁₀: 10.77 µg/m³
O₃: 0.048 ppm
NO₂: 2.4 ppb
SO₂: 0.9 ppb
CO: 0.11 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

7 PM

40 AQI

Good air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 9.57 µg/m³
PM₁₀: 10.45 µg/m³
O₃: 0.042 ppm
NO₂: 3.5 ppb
SO₂: 0.7 ppb
CO: 0.12 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

8 PM

37 AQI

Good air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 8.92 µg/m³
PM₁₀: 9.86 µg/m³
O₃: 0.037 ppm
NO₂: 3.9 ppb
SO₂: 0.6 ppb
CO: 0.12 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

9 PM

35 AQI

Good air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 8.31 µg/m³
PM₁₀: 9.28 µg/m³
O₃: 0.034 ppm
NO₂: 3.7 ppb
SO₂: 0.5 ppb
CO: 0.12 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

10 PM

32 AQI

Good air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 7.75 µg/m³
PM₁₀: 8.74 µg/m³
O₃: 0.033 ppm
NO₂: 3.4 ppb
SO₂: 0.5 ppb
CO: 0.12 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

11 PM

31 AQI

Good air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 7.33 µg/m³
PM₁₀: 8.31 µg/m³
O₃: 0.033 ppm
NO₂: 3 ppb
SO₂: 0.5 ppb
CO: 0.12 ppm

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Current Real-Time Air Quality Report

Weather Alerts and Warnings for Decatur

Moderate Expected Likely

Heat Advisory

Heat Advisory issued September 1 at 2:48AM CDT until September 3 at 7:00PM CDT by NWS Lincoln IL

Sep 1, 2:48 AM → Sep 3, 7:00 PM

WHAT: Afternoon Heat index values up to 105, only falling into the
mid to upper 70s at night.

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

WHEN: Until 7 PM CDT Thursday.

IMPACTS: Hot temperatures and high humidity may cause heat
illnesses.

+ Read More

Take extra precautions when outside. Wear lightweight and loose fitting clothing. Try to limit strenuous activities to early morning or evening. Take action when you see symptoms of heat exhaustion and heat stroke.

Updated: Sep 1, 9:58 AM Source: NWS Alert

Hourly Air Quality Forecast - AQI (US EPA)

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Weather Alerts and Warnings for Decatur

Heat Advisory

Explore U.S. Weather Trends