Severe Thunderstorm Watch 10:00 PM

McHenry County, Illinois, United States

Last updated: 9:13 PM CDT  ·  Refresh
20°C
Feels like 21°
Mostly Cloudy
▲ 24°  /  ▼ 15°
Wind
7 mph WSW
Humidity
94%
Dew Point
19°
Pressure
28.97 inHg
Visibility
10 mi
UV Index
0.0
Cloud Cover
69%
Sunrise
6:07 AM
Sunset
7:45 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: McHenry County is currently mostly cloudy at 20°C. Precipitation is likely — peak probability 58% around 9 PM. Atmospheric instability is elevated (CAPE up to 1227 J/kg) — isolated convective development possible. Sunrise: 6:07AM · Sunset: 7:45PM.

Alerts

Severe Thunderstorm Watch
Expires 10:00 PM
55 AQI · Moderate Dominant: PM2.5 Air Quality
Hourly Forecast · Next 24 Hours
Now
20°
58%
10 PM
20°
41%
11 PM
19°
27%
12 AM
19°
19%
1 AM
18°
3%
2 AM
18°
3%
3 AM
17°
3%
4 AM
17°
4%
5 AM
16°
4%
6 AM
16°
5%
7 AM
16°
5%
8 AM
17°
5%
9 AM
19°
8%
10 AM
21°
8%
11 AM
22°
8%
12 PM
23°
8%
1 PM
26°
12%
2 PM
26°
20%
3 PM
26°
20%
4 PM
27°
10%
5 PM
26°
5%
6 PM
25°
5%
7 PM
24°
3%
8 PM
23°
3%
7-Day Forecast
Tonight
24° 15°
Mostly Cloudy with a 58% chance of rain.
Sat
27° 14°
Partly Cloudy with a 20% chance of rain.
Sun
23° 11°
Partly Cloudy.
Mon
22° 10°
Mostly Cloudy with a 44% chance of rain.
Tue
24° 12°
Clear with a 64% chance of rain.
Wed
27° 14°
Rain, 64% chance.
Thu
27° 16°
Clear.
TimeTempConditionsPrecipWindHumidity
Now 20° Mostly Cloudy 58% 7 mph WSW 94%
10 PM 20° Partly Cloudy 41% 6 mph WSW 95%
11 PM 19° Partly Cloudy 27% 7 mph W 95%
12 AM 19° Mostly Clear 19% 7 mph W 95%
1 AM 18° Partly Cloudy 3% 7 mph WNW 96%
2 AM 18° Partly Cloudy 3% 8 mph WNW 97%
3 AM 17° Partly Cloudy 3% 7 mph NW 97%
4 AM 17° Partly Cloudy 4% 7 mph NW 97%
5 AM 16° Partly Cloudy 4% 7 mph NW 96%
6 AM 16° Partly Cloudy 5% 7 mph NW 96%
7 AM 16° Partly Cloudy 5% 8 mph NW 94%
8 AM 17° Partly Cloudy 5% 9 mph NW 88%
9 AM 19° Partly Cloudy 8% 10 mph NW 82%
10 AM 21° Partly Cloudy 8% 10 mph NW 77%
11 AM 22° Partly Cloudy 8% 11 mph NW 71%
12 PM 23° Partly Cloudy 8% 12 mph NW 66%
1 PM 26° Mostly Clear 12% 13 mph NW 63%
2 PM 26° Mostly Clear 20% 14 mph NW 62%
3 PM 26° Mostly Clear 20% 14 mph NW 59%
4 PM 27° Mostly Clear 10% 13 mph NW 58%
5 PM 26° Mostly Clear 5% 12 mph NW 60%
6 PM 25° Mostly Clear 5% 12 mph NW 64%
7 PM 24° Partly Cloudy 3% 11 mph NW 64%
8 PM 23° Partly Cloudy 3% 10 mph NW 67%
15-Day Forecast
Today
8/21
Mostly Cloudy
58%
15°
24°
Sat
8/22
Partly Cloudy
20%
14°
27°
Sun
8/23
Partly Cloudy
3%
11°
23°
Mon
8/24
Mostly Cloudy
44%
10°
22°
Tue
8/25
Clear
64%
12°
24°
Wed
8/26
Rain
64%
14°
27°
Thu
8/27
Clear
17%
16°
27°
Fri
8/28
Clear
17%
16°
27°
Sat
8/29
Drizzle
68%
16°
27°
Sun
8/30
Rain
68%
18°
28°
Mon
8/31
Drizzle
60%
18°
29°
Tue
9/1
Drizzle
60%
18°
29°
Wed
9/2
Drizzle
60%
17°
26°
Thu
9/3
Drizzle
60%
16°
26°
Fri
9/4
Drizzle
60%
16°
26°
55
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
55 AQI 11.4 µg/m³
O3
Ground-level ozone
37 AQI 41 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Today 55 Moderate 37 55
Sun 30 Good 30 19
Mon 25 Good 25 11
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 Sat Aug 22, 01:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 50 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE972 J/kg
MLCAPE1654 J/kg
MUCAPE2018 J/kg
SBCIN-105 J/kg
MLCIN-40 J/kg
Lifted Index-2.7
Kinematics
0–6 km Shear38 kt
0–1 km Shear11 kt
Eff. Shear35 kt
0–1 km SRH73
0–3 km SRH82
Eff. SRH82
Storm Motion336° @ 20 kt
0–1 km EHI0.4
Composite Parameters
Sig. Tornado0.3
STP (eff)0.6
Supercell3.0
K-Index36.9
Thermo & Levels
PWAT1.55 in
0–3 km LR5.4 °C/km
700–500 LR5.9 °C/km
Total Totals50.6
LCL967 hPa
LFC790 hPa
EL229 hPa
Freezing Lvl11,850 ft