McHenry County, Illinois, United States

Last updated: 9:33 PM CDT  ·  Refresh
24°C
Feels like 26°
Mostly Clear
▲ 29°  /  ▼ 19°
Wind
9 mph SW
Humidity
82%
Dew Point
22°
Pressure
28.71 inHg
Visibility
10 mi
UV Index
0.0
Cloud Cover
14%
Sunrise
5:41 AM
Sunset
8:18 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: McHenry County is currently mostly clear at 25°C. Dry conditions are expected through the next 24 hours. Atmospheric instability is elevated (CAPE up to 1145 J/kg) — isolated convective development possible. Sunrise: 5:41AM · Sunset: 8:18PM.

Alerts

No active alerts for this location.
49 AQI · Good Dominant: PM2.5 Air Quality
Hourly Forecast · Next 24 Hours
Now
24°
36%
10 PM
24°
23%
11 PM
24°
24%
12 AM
23°
16%
1 AM
22°
5%
2 AM
22°
3%
3 AM
22°
3%
4 AM
21°
3%
5 AM
19°
3%
6 AM
19°
3%
7 AM
19°
3%
8 AM
21°
3%
9 AM
22°
3%
10 AM
23°
3%
11 AM
24°
3%
12 PM
26°
3%
1 PM
24°
3%
2 PM
24°
3%
3 PM
24°
3%
4 PM
24°
3%
5 PM
26°
3%
6 PM
24°
3%
7 PM
23°
3%
8 PM
22°
3%
7-Day Forecast
Tonight
29° 19°
Mostly Clear with a 36% chance of rain.
Tue
26° 17°
Partly Cloudy.
Wed
29° 16°
Clear.
Thu
29° 19°
Partly Cloudy.
Fri
24° 18°
Drizzle, 69% chance.
Sat
29° 17°
Drizzle, 69% chance.
Sun
27° 16°
Clear.
TimeTempConditionsPrecipWindHumidity
Now 24° Mostly Clear 36% 9 mph SW 82%
10 PM 24° Clear 23% 8 mph WSW 84%
11 PM 24° Clear 24% 8 mph WNW 85%
12 AM 23° Clear 16% 7 mph NNW 86%
1 AM 22° Mostly Clear 5% 9 mph N 88%
2 AM 22° Partly Cloudy 3% 11 mph N 89%
3 AM 22° Partly Cloudy 3% 12 mph NNE 91%
4 AM 21° Mostly Cloudy 3% 12 mph NNE 91%
5 AM 19° Mostly Cloudy 3% 11 mph N 90%
6 AM 19° Mostly Cloudy 3% 10 mph N 90%
7 AM 19° Mostly Cloudy 3% 10 mph N 86%
8 AM 21° Mostly Cloudy 3% 11 mph N 79%
9 AM 22° Partly Cloudy 3% 12 mph NNE 72%
10 AM 23° Partly Cloudy 3% 12 mph NNE 66%
11 AM 24° Mostly Clear 3% 12 mph NNE 62%
12 PM 26° Clear 3% 12 mph NNE 58%
1 PM 24° Clear 3% 12 mph NNE 55%
2 PM 24° Clear 3% 12 mph NNE 53%
3 PM 24° Clear 3% 12 mph NNE 50%
4 PM 24° Clear 3% 11 mph NNE 50%
5 PM 26° Clear 3% 11 mph NNE 53%
6 PM 24° Clear 3% 10 mph NNE 55%
7 PM 23° Clear 3% 10 mph NE 58%
8 PM 22° Mostly Clear 3% 9 mph NE 62%
15-Day Forecast
Today
7/27
Mostly Clear
36%
19°
29°
Tue
7/28
Partly Cloudy
16%
17°
26°
Wed
7/29
Clear
14%
16°
29°
Thu
7/30
Partly Cloudy
17%
19°
29°
Fri
7/31
Drizzle
69%
18°
24°
Sat
8/1
Drizzle
69%
17°
29°
Sun
8/2
Clear
8%
16°
27°
Mon
8/3
Clear
17%
16°
28°
Tue
8/4
Drizzle
44%
18°
29°
Wed
8/5
Drizzle
68%
19°
30°
Thu
8/6
Rain
64%
17°
28°
Fri
8/7
Drizzle
60%
16°
28°
Sat
8/8
Drizzle
60%
17°
28°
Sun
8/9
Drizzle
60%
18°
28°
Mon
8/10
Drizzle
60%
18°
28°
49
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
49 AQI 8.9 µg/m³
O3
Ground-level ozone
42 AQI 45 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Today 49 Good 42 49
Wed 35 Good 35 27
Thu 39 Good 39 38
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 Tue Jul 28, 01:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 50 60 70 80 90 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE778 J/kg
MLCAPE2512 J/kg
MUCAPE3726 J/kg
SBCIN-307 J/kg
MLCIN0 J/kg
Lifted Index-2.9
Kinematics
0–6 km Shear49 kt
0–1 km Shear19 kt
Eff. Shear58 kt
0–1 km SRH33
0–3 km SRH3
Eff. SRH-77
Storm Motion284° @ 34 kt
0–1 km EHI0.2
Composite Parameters
Sig. Tornado0.2
STP (eff)0.0
Supercell0.0
K-Index37.0
Thermo & Levels
PWAT1.92 in
0–3 km LR4.3 °C/km
700–500 LR6.4 °C/km
Total Totals52.4
LCL936 hPa
LFC585 hPa
EL251 hPa
Freezing Lvl15,892 ft