Severe Thunderstorm Watch 11:00 PM

Fairfax County, Virginia, United States

Last updated: 10:35 PM CDT  ·  Refresh
22°C
Feels like 23°
Haze
▲ 32°  /  ▼ 21°
Wind
8 mph SSW
Humidity
93%
Dew Point
21°
Pressure
29.40 inHg
Visibility
1 mi
UV Index
0.0
Cloud Cover
97%
Sunrise
6:01 AM
Sunset
8:29 PM
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WeatherAI™ Analysis

WeatherAI Analysis: Fairfax County is currently haze at 22°C. Precipitation is likely — peak probability 57% around 1 AM. Atmospheric instability is elevated (CAPE up to 1035 J/kg) — isolated convective development possible. Sunrise: 6:01AM · Sunset: 8:29PM.

Alerts

Severe Thunderstorm Watch
Expires 11:00 PM
38 AQI · Good Dominant: O3 Air Quality
Hourly Forecast · Next 24 Hours
Now
22°
48%
12 AM
23°
57%
1 AM
23°
57%
2 AM
23°
52%
3 AM
23°
21%
4 AM
22°
28%
5 AM
21°
34%
6 AM
22°
39%
7 AM
22°
39%
8 AM
24°
40%
9 AM
24°
36%
10 AM
26°
37%
11 AM
27°
33%
12 PM
28°
34%
1 PM
29°
23%
2 PM
29°
23%
3 PM
29°
24%
4 PM
29°
24%
5 PM
29°
24%
6 PM
27°
21%
7 PM
27°
21%
8 PM
26°
21%
9 PM
26°
22%
10 PM
25°
12%
7-Day Forecast
Tonight
32° 21°
Haze with a 48% chance of rain.
Wed
31° 21°
Partly Cloudy with a 52% chance of rain.
Thu
28° 18°
Clear.
Fri
29° 17°
Overcast with a 37% chance of rain.
Sat
28° 19°
Partly Cloudy with a 26% chance of rain.
Sun
32° 19°
Rain, 82% chance.
Mon
34° 20°
Rain, 64% chance.
TimeTempConditionsPrecipWindHumidity
Now 22° Haze 48% 8 mph SSW 93%
12 AM 23° Rain 57% 8 mph SSW 93%
1 AM 23° Rain 57% 10 mph SW 93%
2 AM 23° Mostly Cloudy 52% 9 mph SW 93%
3 AM 23° Partly Cloudy 21% 8 mph SSW 94%
4 AM 22° Partly Cloudy 28% 7 mph SSW 95%
5 AM 21° Partly Cloudy 34% 6 mph SW 95%
6 AM 22° Partly Cloudy 39% 6 mph SW 94%
7 AM 22° Partly Cloudy 39% 6 mph SW 92%
8 AM 24° Partly Cloudy 40% 6 mph WSW 86%
9 AM 24° Partly Cloudy 36% 7 mph W 79%
10 AM 26° Mostly Cloudy 37% 7 mph W 71%
11 AM 27° Partly Cloudy 33% 7 mph W 64%
12 PM 28° Partly Cloudy 34% 8 mph W 57%
1 PM 29° Partly Cloudy 23% 9 mph W 50%
2 PM 29° Partly Cloudy 23% 9 mph W 48%
3 PM 29° Partly Cloudy 24% 9 mph WNW 49%
4 PM 29° Partly Cloudy 24% 8 mph WNW 51%
5 PM 29° Partly Cloudy 24% 8 mph WNW 53%
6 PM 27° Partly Cloudy 21% 7 mph NW 55%
7 PM 27° Partly Cloudy 21% 7 mph NW 57%
8 PM 26° Partly Cloudy 21% 7 mph NW 58%
9 PM 26° Partly Cloudy 22% 7 mph NNW 57%
10 PM 25° Partly Cloudy 12% 8 mph NNW 57%
15-Day Forecast
Today
7/21
Haze
48%
21°
32°
Wed
7/22
Partly Cloudy
52%
21°
31°
Thu
7/23
Clear
3%
18°
28°
Fri
7/24
Overcast
37%
17°
29°
Sat
7/25
Partly Cloudy
26%
19°
28°
Sun
7/26
Rain
82%
19°
32°
Mon
7/27
Rain
64%
20°
34°
Tue
7/28
Thunderstorm
71%
21°
36°
Wed
7/29
Drizzle
44%
19°
31°
Thu
7/30
Drizzle
44%
19°
31°
Fri
7/31
Drizzle
60%
18°
31°
Sat
8/1
Drizzle
60%
19°
31°
Sun
8/2
Drizzle
60%
19°
31°
Mon
8/3
Drizzle
60%
20°
32°
Tue
8/4
Drizzle
60%
21°
33°
38
Good
U.S. Air Quality Index · Dominant: O3
50 100 150 200

Air quality is satisfactory and poses little or no health risk.

Pollutant Breakdown · Today
PM2.5
Fine particulate matter
23 AQI 4.2 µg/m³
O3
Ground-level ozone
Dominant
38 AQI 42 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Today 38 Good 38 23
Thu 37 Good 37 12
Fri 44 Good 44 22
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 Wed Jul 22, 02:00'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
SBCAPE62 J/kg
MLCAPE173 J/kg
MUCAPE331 J/kg
SBCIN-220 J/kg
MLCIN0 J/kg
Lifted Index-0.4
Kinematics
0–6 km Shear37 kt
0–1 km Shear26 kt
Eff. Shear15 kt
0–1 km SRH-11
0–3 km SRH-22
Eff. SRH-21
Storm Motion241° @ 36 kt
0–1 km EHI-0.0
Composite Parameters
Sig. Tornado0.0
STP (eff)0.0
Supercell0.0
K-Index33.8
Thermo & Levels
PWAT1.95 in
0–3 km LR4.5 °C/km
700–500 LR5.6 °C/km
Total Totals46.1
LCL978 hPa
LFC668 hPa
EL414 hPa
Freezing Lvl14,511 ft