Severe Thunderstorm Watch 12:00 AM

Fairfax County, Virginia, United States

Last updated: 11:56 PM CDT  ·  Refresh
22°C
Feels like 23°
Overcast
▲ 31°  /  ▼ 18°
Wind
8 mph SSW
Humidity
93%
Dew Point
21°
Pressure
29.40 inHg
Visibility
10 mi
UV Index
0.0
Cloud Cover
92%
Sunrise
6:01 AM
Sunset
8:28 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: Fairfax County is currently overcast at 22°C. Precipitation is likely — peak probability 54% around 1 AM. Atmospheric instability is elevated (CAPE up to 1122 J/kg) — isolated convective development possible. Sunrise: 6:01AM · Sunset: 8:28PM.

Alerts

Severe Thunderstorm Watch
Expires 12:00 AM
38 AQI · Good Dominant: O3 Air Quality
Hourly Forecast · Next 24 Hours
Now
22°
34%
1 AM
23°
54%
2 AM
23°
53%
3 AM
23°
25%
4 AM
22°
28%
5 AM
21°
32%
6 AM
22°
38%
7 AM
23°
39%
8 AM
24°
39%
9 AM
24°
36%
10 AM
26°
31%
11 AM
27°
32%
12 PM
28°
30%
1 PM
29°
23%
2 PM
29°
23%
3 PM
29°
23%
4 PM
29°
24%
5 PM
29°
24%
6 PM
28°
20%
7 PM
27°
21%
8 PM
26°
21%
9 PM
26°
11%
10 PM
25°
12%
11 PM
24°
12%
7-Day Forecast
Today
31° 18°
Partly Cloudy with a 38% chance of rain.
Thu
28° 18°
Mostly Clear.
Fri
29° 17°
Mostly Cloudy with a 36% chance of rain.
Sat
28° 19°
Partly Cloudy with a 44% chance of rain.
Sun
32° 19°
Rain, 82% chance.
Mon
34° 20°
Rain, 64% chance.
Tue
36° 21°
Thunderstorm, 71% chance.
TimeTempConditionsPrecipWindHumidity
Now 22° Overcast 34% 8 mph SSW 93%
1 AM 23° Thunderstorm 54% 10 mph SW 93%
2 AM 23° Mostly Cloudy 53% 8 mph SW 94%
3 AM 23° Partly Cloudy 25% 8 mph SW 95%
4 AM 22° Partly Cloudy 28% 6 mph SSW 95%
5 AM 21° Partly Cloudy 32% 6 mph SW 94%
6 AM 22° Mostly Cloudy 38% 6 mph SW 93%
7 AM 23° Partly Cloudy 39% 7 mph WSW 91%
8 AM 24° Partly Cloudy 39% 6 mph WSW 84%
9 AM 24° Mostly Cloudy 36% 7 mph W 76%
10 AM 26° Mostly Cloudy 31% 7 mph W 68%
11 AM 27° Partly Cloudy 32% 8 mph W 61%
12 PM 28° Partly Cloudy 30% 8 mph W 55%
1 PM 29° Partly Cloudy 23% 9 mph W 48%
2 PM 29° Partly Cloudy 23% 8 mph WNW 48%
3 PM 29° Partly Cloudy 23% 8 mph WNW 50%
4 PM 29° Partly Cloudy 24% 8 mph WNW 52%
5 PM 29° Partly Cloudy 24% 7 mph NW 54%
6 PM 28° Partly Cloudy 20% 6 mph NW 56%
7 PM 27° Partly Cloudy 21% 6 mph NW 58%
8 PM 26° Partly Cloudy 21% 7 mph NNW 58%
9 PM 26° Partly Cloudy 11% 7 mph NNW 57%
10 PM 25° Mostly Cloudy 12% 7 mph NNW 56%
11 PM 24° Partly Cloudy 12% 8 mph NNW 56%
15-Day Forecast
Today
7/22
Partly Cloudy
38%
18°
31°
Thu
7/23
Mostly Clear
10%
18°
28°
Fri
7/24
Mostly Cloudy
36%
17°
29°
Sat
7/25
Partly Cloudy
44%
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
Rain
63%
19°
31°
Thu
7/30
Drizzle
44%
19°
31°
Fri
7/31
Drizzle
51%
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°
Wed
8/5
Drizzle
60%
21°
32°
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, 03:00'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
SBCAPE83 J/kg
MLCAPE116 J/kg
MUCAPE184 J/kg
SBCIN-222 J/kg
MLCIN0 J/kg
Lifted Index-0.5
Kinematics
0–6 km Shear36 kt
0–1 km Shear27 kt
Eff. Shear15 kt
0–1 km SRH-12
0–3 km SRH-15
Eff. SRH-30
Storm Motion231° @ 33 kt
0–1 km EHI-0.0
Composite Parameters
Sig. Tornado0.0
STP (eff)0.0
Supercell0.0
K-Index34.1
Thermo & Levels
PWAT1.88 in
0–3 km LR4.5 °C/km
700–500 LR5.6 °C/km
Total Totals45.3
LCL981 hPa
LFC692 hPa
EL462 hPa
Freezing Lvl14,327 ft