Extreme Heat Warning — Clinton, IL, Washington, IL, Randolph, IL, Madison, IL, St. Clair, IL, Monroe, IL, Boone, MO, Moniteau, MO, Cole, MO, Osage, MO, Callaway, MO, Montgomery, MO, Gasconade, MO, Warren, MO, St. Charles, MO, Franklin, MO, St. Louis, MO, St. Louis City, MO, Jefferson, MO 8:00 PM

Jefferson County, Missouri, United States

Last updated: 5:14 AM CDT  ·  Refresh
26°C
Feels like 27°
Mostly Clear
▲ 36°  /  ▼ 24°
Wind
6 mph SSW
Humidity
72%
Dew Point
21°
Pressure
29.28 inHg
Visibility
10 mi
UV Index
0.0
Cloud Cover
12%
Sunrise
6:13 AM
Sunset
8:00 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: Jefferson County is currently mostly clear at 25°C. Dry conditions are expected through the next 24 hours. Atmospheric instability is elevated (CAPE up to 2565 J/kg) — isolated convective development possible. Sunrise: 6:13AM · Sunset: 8:00PM.

Alerts

Extreme Heat Warning
Clinton, IL, Washington, IL, Randolph, IL, Madison, IL, St. Clair, IL, Monroe, IL, Boone, MO, Moniteau, MO, Cole, MO, Osage, MO, Callaway, MO, Montgomery, MO, Gasconade, MO, Warren, MO, St. Charles, MO, Franklin, MO, St. Louis, MO, St. Louis City, MO, Jefferson, MO
Expires 8:00 PM
35 AQI · Good Dominant: PM2.5 Air Quality
Hourly Forecast · Next 24 Hours
Now
26°
7%
6 AM
23°
23%
7 AM
23°
20%
8 AM
26°
20%
9 AM
28°
20%
10 AM
29°
20%
11 AM
31°
20%
12 PM
32°
14%
1 PM
34°
3%
2 PM
35°
3%
3 PM
36°
3%
4 PM
36°
4%
5 PM
35°
5%
6 PM
34°
5%
7 PM
33°
5%
8 PM
31°
13%
9 PM
29°
22%
10 PM
29°
22%
11 PM
28°
22%
12 AM
27°
23%
1 AM
27°
23%
2 AM
26°
24%
3 AM
26°
24%
4 AM
26°
24%
7-Day Forecast
Today
36° 24°
Mostly Clear with a 22% chance of rain.
Wed
38° 24°
Mostly Clear with a 55% chance of rain.
Thu
37° 24°
Mostly Clear.
Fri
34° 23°
Clear.
Sat
39° 23°
Mostly Clear.
Sun
39° 23°
Mostly Clear with a 25% chance of rain.
Mon
34° 21°
Mostly Cloudy with a 25% chance of rain.
TimeTempConditionsPrecipWindHumidity
Now 26° Mostly Clear 7% 6 mph SSW 72%
6 AM 23° Clear 23% 6 mph SW 71%
7 AM 23° Mostly Clear 20% 7 mph SW 71%
8 AM 26° Mostly Clear 20% 8 mph SW 65%
9 AM 28° Mostly Clear 20% 9 mph SW 59%
10 AM 29° Mostly Clear 20% 9 mph WSW 54%
11 AM 31° Mostly Clear 20% 9 mph WSW 51%
12 PM 32° Mostly Clear 14% 10 mph WSW 46%
1 PM 34° Mostly Clear 3% 10 mph SW 43%
2 PM 35° Mostly Clear 3% 9 mph SW 41%
3 PM 36° Mostly Clear 3% 9 mph SW 40%
4 PM 36° Partly Cloudy 4% 9 mph SW 40%
5 PM 35° Partly Cloudy 5% 8 mph SW 43%
6 PM 34° Partly Cloudy 5% 7 mph SW 47%
7 PM 33° Partly Cloudy 5% 6 mph SSW 50%
8 PM 31° Partly Cloudy 13% 6 mph SSW 52%
9 PM 29° Partly Cloudy 22% 6 mph SSW 53%
10 PM 29° Mostly Clear 22% 6 mph SSW 55%
11 PM 28° Partly Cloudy 22% 6 mph SSW 59%
12 AM 27° Partly Cloudy 23% 6 mph SSW 62%
1 AM 27° Partly Cloudy 23% 6 mph SSW 65%
2 AM 26° Partly Cloudy 24% 6 mph SSW 66%
3 AM 26° Mostly Clear 24% 6 mph SSW 66%
4 AM 26° Mostly Clear 24% 6 mph SSW 67%
15-Day Forecast
Today
8/11
Mostly Clear
22%
24°
36°
Wed
8/12
Mostly Clear
55%
24°
38°
Thu
8/13
Mostly Clear
15%
24°
37°
Fri
8/14
Clear
15%
23°
34°
Sat
8/15
Mostly Clear
15%
23°
39°
Sun
8/16
Mostly Clear
25%
23°
39°
Mon
8/17
Mostly Cloudy
25%
21°
34°
Tue
8/18
Drizzle
53%
19°
38°
Wed
8/19
Partly Cloudy
35%
21°
39°
Thu
8/20
Mostly Clear
35%
23°
38°
Fri
8/21
Clear
60%
21°
38°
Sat
8/22
Drizzle
60%
21°
35°
Sun
8/23
Clear
60%
21°
35°
Mon
8/24
Drizzle
60%
21°
33°
Tue
8/25
Drizzle
60%
20°
33°
35
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
35 AQI 6.3 µg/m³
O3
Ground-level ozone
34 AQI 37 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Today 35 Good 34 35
Wed 32 Good 32 17
Thu 31 Good 31 23
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 Aug 11, 09:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE1241 J/kg
MLCAPE1217 J/kg
MUCAPE1262 J/kg
SBCIN-477 J/kg
MLCIN0 J/kg
Lifted Index-5.9
Kinematics
0–6 km Shear19 kt
0–1 km Shear18 kt
Eff. Shear17 kt
0–1 km SRH148
0–3 km SRH125
Eff. SRH-27
Storm Motion315° @ 16 kt
0–1 km EHI1.2
Composite Parameters
Sig. Tornado0.0
STP (eff)0.0
Supercell0.0
K-Index30.3
Thermo & Levels
PWAT1.60 in
0–3 km LR4.3 °C/km
700–500 LR8.3 °C/km
Total Totals55.7
LCL931 hPa
LFC645 hPa
EL204 hPa
Freezing Lvl14,616 ft