Heat Advisory — Jefferson, IL, Perry, IL, Franklin, IL, Jackson, IL, Williamson, IL, Union, IL, Johnson, IL, Pope, IL, Alexander, IL, Pulaski, IL, Massac, IL, Fulton, KY, Hickman, KY, Carlisle, KY, Ballard, KY, McCracken, KY, Graves, KY, Livingston, KY, Marshall, KY, Calloway, 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 7:00 PM

Williamson County, Illinois, United States

Last updated: 12:14 PM CDT  ·  Refresh
33°C
Feels like 42°
Partly Cloudy
▲ 36°  /  ▼ 23°
Wind
5 mph SW
Humidity
69%
Dew Point
26°
Pressure
29.46 inHg
Visibility
10 mi
UV Index
9.0
Cloud Cover
42%
Sunrise
5:54 AM
Sunset
8:09 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: Williamson County is currently partly cloudy at 33°C. Precipitation is likely — peak probability 50% around 9 PM. Atmospheric instability is elevated (CAPE up to 4441 J/kg) — isolated convective development possible. Sunrise: 5:54AM · Sunset: 8:09PM.

Alerts

Heat Advisory
Jefferson, IL, Perry, IL, Franklin, IL, Jackson, IL, Williamson, IL, Union, IL, Johnson, IL, Pope, IL, Alexander, IL, Pulaski, IL, Massac, IL, Fulton, KY, Hickman, KY, Carlisle, KY, Ballard, KY, McCracken, KY, Graves, KY, Livingston, KY, Marshall, KY, Calloway, 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 7:00 PM
52 AQI · Moderate Dominant: PM2.5 Air Quality
Hourly Forecast · Next 24 Hours
Now
33°
14%
1 PM
34°
26%
2 PM
34°
33%
3 PM
35°
36%
4 PM
36°
35%
5 PM
36°
35%
6 PM
35°
30%
7 PM
34°
45%
8 PM
33°
45%
9 PM
30°
50%
10 PM
30°
50%
11 PM
29°
45%
12 AM
28°
33%
1 AM
26°
24%
2 AM
26°
25%
3 AM
25°
25%
4 AM
24°
16%
5 AM
23°
12%
6 AM
24°
12%
7 AM
24°
3%
8 AM
26°
10%
9 AM
28°
10%
10 AM
29°
21%
11 AM
31°
22%
7-Day Forecast
Today
36° 23°
Partly Cloudy with a 50% chance of rain.
Mon
37° 23°
Mostly Clear with a 40% chance of rain.
Tue
36° 22°
Mostly Clear with a 44% chance of rain.
Wed
30° 19°
Clear with a 44% chance of rain.
Thu
32° 18°
Clear with a 22% chance of rain.
Fri
29° 20°
Rain, 90% chance.
Sat
30° 19°
Drizzle, 81% chance.
TimeTempConditionsPrecipWindHumidity
Now 33° Partly Cloudy 14% 5 mph SW 69%
1 PM 34° Partly Cloudy 26% 5 mph WSW 63%
2 PM 34° Partly Cloudy 33% 6 mph WSW 63%
3 PM 35° Partly Cloudy 36% 7 mph WSW 61%
4 PM 36° Partly Cloudy 35% 7 mph WSW 60%
5 PM 36° Mostly Clear 35% 6 mph SW 64%
6 PM 35° Mostly Clear 30% 5 mph SW 69%
7 PM 34° Partly Cloudy 45% 4 mph SSW 75%
8 PM 33° Mostly Cloudy 45% 5 mph SSW 77%
9 PM 30° Partly Cloudy 50% 5 mph SSW 79%
10 PM 30° Mostly Cloudy 50% 5 mph SW 81%
11 PM 29° Mostly Cloudy 45% 4 mph S 85%
12 AM 28° Mostly Cloudy 33% 5 mph SE 89%
1 AM 26° Mostly Cloudy 24% 7 mph SE 92%
2 AM 26° Partly Cloudy 25% 7 mph SE 92%
3 AM 25° Mostly Cloudy 25% 7 mph SSE 91%
4 AM 24° Mostly Cloudy 16% 7 mph S 90%
5 AM 23° Partly Cloudy 12% 6 mph S 89%
6 AM 24° Partly Cloudy 12% 6 mph SSW 89%
7 AM 24° Partly Cloudy 3% 7 mph SSW 87%
8 AM 26° Partly Cloudy 10% 7 mph SW 82%
9 AM 28° Partly Cloudy 10% 7 mph SW 78%
10 AM 29° Mostly Clear 21% 7 mph SW 74%
11 AM 31° Partly Cloudy 22% 6 mph SW 71%
15-Day Forecast
Today
7/26
Partly Cloudy
50%
23°
36°
Mon
7/27
Mostly Clear
40%
23°
37°
Tue
7/28
Mostly Clear
44%
22°
36°
Wed
7/29
Clear
44%
19°
30°
Thu
7/30
Clear
22%
18°
32°
Fri
7/31
Rain
90%
20°
29°
Sat
8/1
Drizzle
81%
19°
30°
Sun
8/2
Drizzle
60%
19°
31°
Mon
8/3
Drizzle
60%
19°
32°
Tue
8/4
Drizzle
60%
21°
34°
Wed
8/5
Drizzle
60%
22°
33°
Thu
8/6
Drizzle
60%
21°
32°
Fri
8/7
Drizzle
60%
21°
32°
Sat
8/8
Drizzle
60%
20°
32°
Sun
8/9
Drizzle
60%
21°
33°
52
Moderate
U.S. Air Quality Index · Dominant: PM2.5
50 100 150 200

Air quality is acceptable. Unusually sensitive people should consider limiting prolonged outdoor exertion.

Pollutant Breakdown · Today
PM2.5
Fine particulate matter
Dominant
52 AQI 9.6 µg/m³
O3
Ground-level ozone
35 AQI 39 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Mon 52 Moderate 35 52
Tue 54 Moderate 33 54
Wed 42 Good 42 39
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 Sun Jul 26, 15:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE5377 J/kg
MLCAPE3410 J/kg
MUCAPE5377 J/kg
SBCIN0 J/kg
MLCIN0 J/kg
Lifted Index-8.9
Kinematics
0–6 km Shear22 kt
0–1 km Shear6 kt
Eff. Shear26 kt
0–1 km SRH-16
0–3 km SRH-53
Eff. SRH-53
Storm Motion293° @ 20 kt
0–1 km EHI-0.6
Composite Parameters
Sig. Tornado0.0
STP (eff)0.0
Supercell0.0
K-Index36.2
Thermo & Levels
PWAT1.94 in
0–3 km LR6.9 °C/km
700–500 LR5.8 °C/km
Total Totals47.6
LCL911 hPa
LFC998 hPa
EL123 hPa
Freezing Lvl16,762 ft