Heat Advisory — Jefferson, IL, Wayne, IL, Edwards, IL, Wabash, IL, Franklin, IL, Hamilton, IL, White, IL, Jackson, IL, Williamson, IL, Saline, IL, Gallatin, IL, Union, IL, Johnson, IL, Pope, IL, Hardin, IL, Alexander, IL, Pulaski, IL, Massac, IL, Gibson, IN, Pike, IN, Posey, IN, Vanderburgh, IN, Warrick, IN, Spencer, IN, Fulton, KY, Hickman, KY, Carlisle, KY, Ballard, KY, McCracken, KY, Graves, KY, Livingston, KY, Marshall, KY, Calloway, KY, Crittenden, KY, Lyon, KY, Trigg, KY, Caldwell, KY, Union, KY, Webster, KY, Hopkins, KY, Christian, KY, Henderson, KY, Daviess, KY, McLean, KY, Muhlenberg, KY, Todd, KY, Perry, MO, Bollinger, MO, Cape Girardeau, MO, Wayne, MO, Carter, MO, Ripley, MO, Butler, MO, Stoddard, MO, Scott, MO, Mississippi, MO, New Madrid, MO 8:00 PM

Williamson County, Illinois, United States

Last updated: 8:07 AM CDT  ·  Refresh
26°C
Feels like 27°
Mostly Clear
▲ 34°  /  ▼ 23°
Wind
9 mph SSW
Humidity
81%
Dew Point
22°
Pressure
29.56 inHg
Visibility
10 mi
UV Index
5.2
Cloud Cover
24%
Sunrise
6:07 AM
Sunset
7:54 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. Atmospheric instability is elevated (CAPE up to 3227 J/kg) — isolated convective development possible. Sunrise: 6:07AM · Sunset: 7:54PM.

Alerts

Heat Advisory
Jefferson, IL, Wayne, IL, Edwards, IL, Wabash, IL, Franklin, IL, Hamilton, IL, White, IL, Jackson, IL, Williamson, IL, Saline, IL, Gallatin, IL, Union, IL, Johnson, IL, Pope, IL, Hardin, IL, Alexander, IL, Pulaski, IL, Massac, IL, Gibson, IN, Pike, IN, Posey, IN, Vanderburgh, IN, Warrick, IN, Spencer, IN, Fulton, KY, Hickman, KY, Carlisle, KY, Ballard, KY, McCracken, KY, Graves, KY, Livingston, KY, Marshall, KY, Calloway, KY, Crittenden, KY, Lyon, KY, Trigg, KY, Caldwell, KY, Union, KY, Webster, KY, Hopkins, KY, Christian, KY, Henderson, KY, Daviess, KY, McLean, KY, Muhlenberg, KY, Todd, KY, Perry, MO, Bollinger, MO, Cape Girardeau, MO, Wayne, MO, Carter, MO, Ripley, MO, Butler, MO, Stoddard, MO, Scott, MO, Mississippi, MO, New Madrid, MO
Expires 8:00 PM
43 AQI · Good Dominant: PM2.5 Air Quality
Hourly Forecast · Next 24 Hours
Now
26°
11%
9 AM
27°
19%
10 AM
28°
20%
11 AM
30°
20%
12 PM
31°
14%
1 PM
33°
3%
2 PM
33°
3%
3 PM
33°
3%
4 PM
33°
4%
5 PM
34°
4%
6 PM
33°
4%
7 PM
32°
6%
8 PM
31°
5%
9 PM
29°
5%
10 PM
28°
3%
11 PM
28°
3%
12 AM
28°
3%
1 AM
27°
3%
2 AM
26°
3%
3 AM
26°
5%
4 AM
26°
5%
5 AM
24°
5%
6 AM
24°
5%
7 AM
24°
5%
7-Day Forecast
Today
34° 23°
Mostly Clear with a 20% chance of rain.
Tue
36° 24°
Clear.
Wed
38° 24°
Partly Cloudy with a 66% chance of rain.
Thu
36° 24°
Partly Cloudy with a 75% chance of rain.
Fri
33° 23°
Partly Cloudy with a 64% chance of rain.
Sat
38° 22°
Clear.
Sun
38° 24°
Clear.
TimeTempConditionsPrecipWindHumidity
Now 26° Mostly Clear 11% 9 mph SSW 81%
9 AM 27° Mostly Clear 19% 11 mph SW 71%
10 AM 28° Mostly Clear 20% 11 mph SW 65%
11 AM 30° Mostly Clear 20% 11 mph SW 61%
12 PM 31° Partly Cloudy 14% 12 mph SW 57%
1 PM 33° Partly Cloudy 3% 12 mph SW 53%
2 PM 33° Partly Cloudy 3% 13 mph SW 52%
3 PM 33° Partly Cloudy 3% 13 mph SW 50%
4 PM 33° Partly Cloudy 4% 12 mph SW 50%
5 PM 34° Partly Cloudy 4% 10 mph SSW 54%
6 PM 33° Partly Cloudy 4% 9 mph SSW 58%
7 PM 32° Mostly Clear 6% 8 mph SSW 63%
8 PM 31° Mostly Clear 5% 8 mph SSW 66%
9 PM 29° Mostly Clear 5% 8 mph SSW 68%
10 PM 28° Mostly Clear 3% 8 mph SSW 70%
11 PM 28° Mostly Clear 3% 9 mph SSW 71%
12 AM 28° Partly Cloudy 3% 9 mph SSW 72%
1 AM 27° Partly Cloudy 3% 10 mph SSW 72%
2 AM 26° Partly Cloudy 3% 10 mph SSW 73%
3 AM 26° Mostly Clear 5% 10 mph SSW 74%
4 AM 26° Mostly Clear 5% 10 mph SSW 76%
5 AM 24° Mostly Clear 5% 10 mph SSW 78%
6 AM 24° Mostly Clear 5% 10 mph SSW 79%
7 AM 24° Clear 5% 10 mph SSW 80%
15-Day Forecast
Today
8/10
Mostly Clear
20%
23°
34°
Tue
8/11
Clear
11%
24°
36°
Wed
8/12
Partly Cloudy
66%
24°
38°
Thu
8/13
Partly Cloudy
75%
24°
36°
Fri
8/14
Partly Cloudy
64%
23°
33°
Sat
8/15
Clear
19%
22°
38°
Sun
8/16
Clear
15%
24°
38°
Mon
8/17
Drizzle
39%
21°
33°
Tue
8/18
Drizzle
58%
19°
34°
Wed
8/19
Thunderstorm
45%
22°
34°
Thu
8/20
Drizzle
60%
22°
35°
Fri
8/21
Drizzle
60%
21°
34°
Sat
8/22
Clear
60%
21°
33°
Sun
8/23
Drizzle
60%
21°
34°
Mon
8/24
Clear
60%
20°
33°
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
41 AQI 45 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Tue 43 Good 41 43
Wed 37 Good 37 19
Thu 37 Good 37 28
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 LCLLFCEL0°C Temperature (°C) Pressure (hPa)
Temp Dewpoint Parcel (SB) CAPE CIN Dry adiabat Moist adiabat Mixing ratio
RAP
Valid Mon Aug 10, 11:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE1746 J/kg
MLCAPE1557 J/kg
MUCAPE1877 J/kg
SBCIN-292 J/kg
MLCIN0 J/kg
Lifted Index-7.2
Kinematics
0–6 km Shear11 kt
0–1 km Shear21 kt
Eff. Shear13 kt
0–1 km SRH143
0–3 km SRH153
Eff. SRH57
Storm Motion17° @ 5 kt
0–1 km EHI1.6
Composite Parameters
Sig. Tornado0.0
STP (eff)0.0
Supercell0.0
K-Index26.1
Thermo & Levels
PWAT1.56 in
0–3 km LR4.4 °C/km
700–500 LR8.1 °C/km
Total Totals52.8
LCL958 hPa
LFC676 hPa
EL191 hPa
Freezing Lvl14,747 ft