Williamson County, Illinois, United States

Last updated: 10:05 PM CDT  ·  Refresh
26°C
Feels like 28°
Mostly Clear
▲ 34°  /  ▼ 19°
Wind
7 mph NNW
Humidity
80%
Dew Point
21°
Pressure
29.38 inHg
Visibility
10 mi
UV Index
0.0
Cloud Cover
22%
Sunrise
5:50 AM
Sunset
8:13 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: Williamson County is currently mostly clear at 26°C. Dry conditions are expected through the next 24 hours. Sunrise: 5:50AM · Sunset: 8:13PM.

Alerts

No active alerts for this location.
43 AQI · Good Dominant: PM2.5 Air Quality
Hourly Forecast · Next 24 Hours
Now
26°
3%
11 PM
24°
14%
12 AM
24°
14%
1 AM
23°
3%
2 AM
22°
3%
3 AM
21°
3%
4 AM
20°
3%
5 AM
19°
3%
6 AM
19°
3%
7 AM
19°
3%
8 AM
21°
3%
9 AM
23°
3%
10 AM
24°
5%
11 AM
25°
5%
12 PM
26°
5%
1 PM
28°
5%
2 PM
28°
5%
3 PM
28°
5%
4 PM
28°
3%
5 PM
28°
3%
6 PM
28°
3%
7 PM
27°
3%
8 PM
26°
3%
9 PM
22°
3%
7-Day Forecast
Tonight
34° 19°
Mostly Clear.
Wed
29° 18°
Partly Cloudy.
Thu
27° 15°
Clear.
Fri
23° 16°
Overcast with a 44% chance of rain.
Sat
30° 18°
Clear with a 45% chance of rain.
Sun
34° 23°
Clear.
Mon
35° 23°
Clear with a 28% chance of rain.
TimeTempConditionsPrecipWindHumidity
Now 26° Mostly Clear 3% 7 mph NNW 80%
11 PM 24° Mostly Clear 14% 7 mph NNW 83%
12 AM 24° Clear 14% 7 mph NNW 84%
1 AM 23° Clear 3% 7 mph NNW 86%
2 AM 22° Clear 3% 6 mph NNW 88%
3 AM 21° Clear 3% 6 mph NNW 90%
4 AM 20° Clear 3% 5 mph NNW 92%
5 AM 19° Clear 3% 5 mph NNW 92%
6 AM 19° Clear 3% 6 mph NNW 91%
7 AM 19° Clear 3% 6 mph N 90%
8 AM 21° Mostly Clear 3% 7 mph N 85%
9 AM 23° Mostly Clear 3% 6 mph NNE 81%
10 AM 24° Partly Cloudy 5% 7 mph NNE 77%
11 AM 25° Partly Cloudy 5% 8 mph NNE 73%
12 PM 26° Mostly Cloudy 5% 9 mph NNE 69%
1 PM 28° Overcast 5% 9 mph NNE 65%
2 PM 28° Overcast 5% 10 mph NNE 63%
3 PM 28° Overcast 5% 10 mph NNE 61%
4 PM 28° Overcast 3% 10 mph NNE 60%
5 PM 28° Mostly Cloudy 3% 10 mph NNE 63%
6 PM 28° Mostly Cloudy 3% 9 mph NNE 66%
7 PM 27° Mostly Cloudy 3% 9 mph NNE 68%
8 PM 26° Mostly Cloudy 3% 9 mph NNE 70%
9 PM 22° Partly Cloudy 3% 8 mph NNE 72%
15-Day Forecast
Today
7/21
Mostly Clear
3%
19°
34°
Wed
7/22
Partly Cloudy
5%
18°
29°
Thu
7/23
Clear
3%
15°
27°
Fri
7/24
Overcast
44%
16°
23°
Sat
7/25
Clear
45%
18°
30°
Sun
7/26
Clear
17%
23°
34°
Mon
7/27
Clear
28%
23°
35°
Tue
7/28
Clear
28%
19°
33°
Wed
7/29
Drizzle
44%
18°
29°
Thu
7/30
Drizzle
44%
16°
29°
Fri
7/31
Drizzle
51%
16°
29°
Sat
8/1
Drizzle
60%
18°
29°
Sun
8/2
Clear
60%
19°
30°
Mon
8/3
Drizzle
60%
19°
31°
Tue
8/4
Drizzle
60%
20°
31°
43
Good
U.S. Air Quality Index · Dominant: PM2.5
50 100 150 200

Air quality is satisfactory and poses little or no health risk.

Pollutant Breakdown · Today
PM2.5
Fine particulate matter
Dominant
43 AQI 7.8 µg/m³
O3
Ground-level ozone
37 AQI 41 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Today 43 Good 37 43
Thu 29 Good 29 16
Fri 35 Good 35 8
About the Air Quality Index
0–50 Good
51–100 Moderate
101–150 Unhealthy for Sensitive Groups
151–200 Unhealthy
201–300 Very Unhealthy
301–500 Hazardous

The U.S. AQI runs 0–500. The overall value equals the highest individual pollutant sub-index, and the dominant pollutant is the one driving it. PM2.5 (fine particles) is reported in µg/m³ and ozone (O3) in ppb. Forecast source: NWS NAQFC.

1000850700500400300250200150100 -40-30-20-10010203040 0.41247101624 LCL0°C Temperature (°C) Pressure (hPa)
Temp Dewpoint Parcel (SB) CAPE CIN Dry adiabat Moist adiabat Mixing ratio
RAP
Valid Wed Jul 22, 01:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 50 60 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE0 J/kg
MLCAPE9 J/kg
MUCAPE102 J/kg
SBCIN-2933 J/kg
MLCIN0 J/kg
Lifted Index2.0
Kinematics
0–6 km Shear41 kt
0–1 km Shear10 kt
Eff. Shear33 kt
0–1 km SRH-81
0–3 km SRH-113
Eff. SRH-44
Storm Motion283° @ 29 kt
0–1 km EHI-0.0
Composite Parameters
Sig. Tornado-0.0
STP (eff)0.0
Supercell0.0
K-Index8.7
Thermo & Levels
PWAT1.42 in
0–3 km LR4.5 °C/km
700–500 LR5.4 °C/km
Total Totals38.4
LCL923 hPa
LFC—
EL—
Freezing Lvl17,359 ft