Excessive Heat Warning — Winnebago, IL, Ogle, IL, Lee, IL, De Kalb, IL, La Salle, IL, Grundy, IL, Livingston, IL, Ford, IL, Lake, IN, Newton, IN, Jasper, IN, Benton, IN, Porter, IN, Boone, IL, McHenry, IL, Kane, IL, Kendall, IL, Lake, IL, DuPage, IL, Kankakee, IL, Iroquois, IL, Northern Cook, IL, Central Cook, IL, Southern Cook, IL, Northern Will, IL, Southern Will, IL, Eastern Will, IL 9:00 PM Flood Warning — Cook County, IL, Lake County, IN 1:00 PM Beach Hazards Statement — Lake, IL, Northern Cook, IL, Central Cook, IL, Lake, IN, Porter, IN 10:00 AM

Cook County, Illinois, United States

Last updated: 7:39 PM CDT  ·  Refresh
25°C
Feels like 26°
Partly Cloudy
▲ 28°  /  ▼ 21°
Wind
12 mph S
Humidity
78%
Dew Point
22°
Pressure
29.04 inHg
Visibility
10 mi
UV Index
1.3
Cloud Cover
55%
Sunrise
5:40 AM
Sunset
8:14 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: Cook County is currently partly cloudy at 25°C. Precipitation is likely — peak probability 66% around 9 PM. Atmospheric instability is elevated (CAPE up to 1755 J/kg) — isolated convective development possible. Sunrise: 5:40AM · Sunset: 8:14PM.

Alerts

Excessive Heat Warning
Winnebago, IL, Ogle, IL, Lee, IL, De Kalb, IL, La Salle, IL, Grundy, IL, Livingston, IL, Ford, IL, Lake, IN, Newton, IN, Jasper, IN, Benton, IN, Porter, IN, Boone, IL, McHenry, IL, Kane, IL, Kendall, IL, Lake, IL, DuPage, IL, Kankakee, IL, Iroquois, IL, Northern Cook, IL, Central Cook, IL, Southern Cook, IL, Northern Will, IL, Southern Will, IL, Eastern Will, IL
Expires 9:00 PM
Flood Warning
Cook County, IL, Lake County, IN
Expires 1:00 PM
Beach Hazards Statement
Lake, IL, Northern Cook, IL, Central Cook, IL, Lake, IN, Porter, IN
Expires 10:00 AM
54 AQI · Moderate Dominant: PM2.5 Air Quality
Hourly Forecast · Next 24 Hours
Now
25°
16%
8 PM
24°
48%
9 PM
26°
66%
10 PM
26°
56%
11 PM
26°
32%
12 AM
26°
17%
1 AM
25°
6%
2 AM
24°
6%
3 AM
23°
6%
4 AM
22°
6%
5 AM
21°
3%
6 AM
21°
3%
7 AM
21°
3%
8 AM
22°
3%
9 AM
22°
3%
10 AM
23°
3%
11 AM
24°
3%
12 PM
24°
3%
1 PM
22°
3%
2 PM
21°
3%
3 PM
22°
3%
4 PM
21°
3%
5 PM
23°
3%
6 PM
23°
3%
7-Day Forecast
Tonight
28° 21°
Partly Cloudy with a 56% chance of rain.
Tue
26° 21°
Partly Cloudy.
Wed
28° 19°
Clear.
Thu
29° 22°
Partly Cloudy with a 25% chance of rain.
Fri
25° 18°
Rain, 64% chance.
Sat
27° 19°
Rain, 82% chance.
Sun
27° 20°
Clear.
TimeTempConditionsPrecipWindHumidity
Now 25° Partly Cloudy 16% 12 mph S 78%
8 PM 24° Partly Cloudy 48% 10 mph SSW 82%
9 PM 26° Partly Cloudy 66% 9 mph SW 87%
10 PM 26° Mostly Clear 56% 9 mph SW 89%
11 PM 26° Mostly Clear 32% 8 mph WSW 88%
12 AM 26° Clear 17% 8 mph WNW 87%
1 AM 25° Mostly Clear 6% 8 mph NNW 87%
2 AM 24° Partly Cloudy 6% 10 mph N 88%
3 AM 23° Partly Cloudy 6% 12 mph N 88%
4 AM 22° Mostly Cloudy 6% 13 mph N 89%
5 AM 21° Mostly Cloudy 3% 12 mph N 88%
6 AM 21° Overcast 3% 12 mph N 87%
7 AM 21° Overcast 3% 12 mph N 84%
8 AM 22° Overcast 3% 12 mph N 80%
9 AM 22° Overcast 3% 13 mph N 75%
10 AM 23° Mostly Cloudy 3% 13 mph N 72%
11 AM 24° Partly Cloudy 3% 13 mph N 68%
12 PM 24° Partly Cloudy 3% 13 mph N 64%
1 PM 22° Mostly Clear 3% 13 mph N 59%
2 PM 21° Mostly Clear 3% 13 mph N 53%
3 PM 22° Mostly Clear 3% 13 mph N 48%
4 PM 21° Mostly Clear 3% 13 mph N 48%
5 PM 23° Mostly Clear 3% 13 mph N 50%
6 PM 23° Mostly Clear 3% 13 mph N 52%
15-Day Forecast
Today
7/27
Partly Cloudy
56%
21°
28°
Tue
7/28
Partly Cloudy
6%
21°
26°
Wed
7/29
Clear
3%
19°
28°
Thu
7/30
Partly Cloudy
25%
22°
29°
Fri
7/31
Rain
64%
18°
25°
Sat
8/1
Rain
82%
19°
27°
Sun
8/2
Clear
17%
20°
27°
Mon
8/3
Clear
8%
19°
28°
Tue
8/4
Drizzle
44%
21°
30°
Wed
8/5
Drizzle
44%
22°
31°
Thu
8/6
Drizzle
60%
22°
31°
Fri
8/7
Drizzle
60%
22°
31°
Sat
8/8
Drizzle
60%
22°
27°
Sun
8/9
Drizzle
60%
22°
26°
Mon
8/10
Drizzle
60%
22°
26°
54
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
54 AQI 10.6 µg/m³
O3
Ground-level ozone
41 AQI 45 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Today 54 Moderate 41 54
Wed 31 Good 31 21
Thu 36 Good 35 36
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 Jul 27, 23:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 50 60 70 80 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE679 J/kg
MLCAPE2209 J/kg
MUCAPE4011 J/kg
SBCIN0 J/kg
MLCIN0 J/kg
Lifted Index-2.7
Kinematics
0–6 km Shear54 kt
0–1 km Shear23 kt
Eff. Shear55 kt
0–1 km SRH149
0–3 km SRH129
Eff. SRH129
Storm Motion279° @ 34 kt
0–1 km EHI0.6
Composite Parameters
Sig. Tornado1.0
STP (eff)0.9
Supercell14.7
K-Index6.1
Thermo & Levels
PWAT1.71 in
0–3 km LR3.8 °C/km
700–500 LR7.2 °C/km
Total Totals54.1
LCL941 hPa
LFC983 hPa
EL253 hPa
Freezing Lvl15,974 ft