Today | Weather | Monday, April 27, 2026
Active Weather Warnings

Weather in St. Charles, Missouri

01:49 PM
Now
Stormy Weather
72° F
Feels Like 70°
Precipitation 61 %
Wind 20 mph
UV Index (0 - 11+) 2
Humidity 78 %
Today
Stormy Weather
Day 82°
Night 54°
Precipitation 99 %
Wind 17 mph
UV Index (0 - 11+) 3

St. Charles Weather Forecast Updated

8 minutes ago
Last updated on

Air Quality in St. Charles

NOW
20 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 1.3 µg/m³
PM10 1.45 µg/m³
O3 0.022 ppm
NO2 0.3 ppb
SO2 0 ppb
CO 0.10 ppm
NH3 0.33 µg/m³
NO 0.12 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.51.3 µg/m³
PM101.45 µg/m³
O342.38 µg/m³
NO20.61 µg/m³
SO20.09 µg/m³
CO116.49 µg/m³
NH30.33 µg/m³
NO0.12 µg/m³

Weather Alerts and Warnings for St. Charles

Extreme Future Possible

Tornado Watch

Tornado Watch issued April 27 at 12:50PM CDT until April 27 at 9:00PM CDT by NWS St Louis MO
Apr 27, 12:50 PM Apr 27, 9:00 PM
THE NATIONAL WEATHER SERVICE HAS ISSUED TORNADO WATCH 160 IN
EFFECT UNTIL 9 PM CDT THIS EVENING FOR THE FOLLOWING AREAS

IN ILLINOIS THIS WATCH INCLUDES 6 COUNTIES

IN SOUTHWEST ILLINOIS

CALHOUN JERSEY MADISON
MONROE RANDOLPH SAINT CLAIR

IN MISSOURI THIS WATCH INCLUDES 20 COUNTIES

IN CENTRAL MISSOURI

CALLAWAY COLE MONITEAU
OSAGE

IN EAST CENTRAL MISSOURI

CRAWFORD FRANKLIN GASCONADE
JEFFERSON LINCOLN MONTGOMERY
SAINT CHARLES SAINT LOUIS SAINT LOUIS CITY
WARREN WASHINGTON

IN SOUTHEAST MISSOURI

IRON MADISON REYNOLDS
SAINT FRANCOIS SAINTE GENEVIEVE

THIS INCLUDES THE CITIES OF ALTON, BELLEVILLE, CAHOKIA, CHESTER,
EDWARDSVILLE, FARMINGTON, FULTON, JEFFERSON CITY, SAINT CHARLES,
SAINT LOUIS, SPARTA, SULLIVAN, UNION, AND WASHINGTON.
Updated: Apr 27, 1:40 PM Source: NWS Alert
Severe Immediate Observed

Severe Thunderstorm Warning

Severe Thunderstorm Warning issued April 27 at 1:37PM CDT until April 27 at 2:15PM CDT by NWS St Louis MO
Apr 27, 1:37 PM Apr 27, 2:15 PM
At 137 PM CDT, a severe thunderstorm was located over Clarkson
Valley, moving east at 30 mph.

HAZARD...Ping pong ball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail
damage to roofs, siding, windows, and vehicles. Expect wind
damage to roofs, siding, and trees.

This severe thunderstorm will be near...
Chesterfield, Clarkson Valley, Ballwin, Wildwood, Ellisville,
Spirit of St. Louis Airport, Weldon Spring and St. Peters around
140 PM CDT.
Manchester, Winchester, Twin Oaks and Valley Park around 145 PM
CDT.
Creve Coeur, Town and Country, Country Life Acres, Des Peres, St.
Charles, Fenton and Sunset Hills around 150 PM CDT.

Other locations impacted by the severe thunderstorm include Peerless
Park.

This includes the following State Parks...
Babler Memorial State Park, Route 66 State Park, Castlewood State
Park and First Missouri State Capitol Historic Site.

This includes the following highways...
Interstate 70 in Missouri between exits 228 and 231. Interstate 44 in
Missouri between exits 261 and 277.
+ Read More
Seek shelter inside a well-built structure and stay away from windows. This storm is capable of producing damaging winds and large hail. Tornadoes can develop quickly from severe thunderstorms. Seek shelter immediately in an interior room on the lowest floor of a well-built structure. A Tornado Watch remains in effect until 900 PM CDT Monday for a portion of east central Missouri.
Updated: Apr 27, 1:40 PM Source: NWS Alert
Severe Future Possible

Flood Watch

Flood Watch issued April 27 at 11:18AM CDT until April 27 at 9:00PM CDT by NWS St Louis MO
Apr 27, 11:18 AM Apr 27, 9:00 PM
WHAT: Flash flooding caused by excessive rainfall is possible.

WHERE: Portions of Illinois, including the following areas, Bond
IL, Calhoun IL, Clinton IL, Fayette IL, Greene IL, Jersey IL,
Macoupin IL, Madison IL, Marion IL, Monroe IL, Montgomery IL, Saint
Clair IL and Washington IL and Missouri, including the following
areas, Audrain MO, Boone MO, Callaway MO, Cole MO, Franklin MO,
Gasconade MO, Jefferson MO, Lincoln MO, Moniteau MO, Montgomery MO,
Osage MO, Pike MO, Saint Charles MO, Saint Louis City MO, Saint
Louis MO and Warren MO.

WHEN: Until 9 PM CDT this evening.

IMPACTS: Excessive runoff may result in flooding of rivers,
creeks, streams, and other low-lying and flood-prone locations.

ADDITIONAL DETAILS:
- Thunderstorms producing heavy rainfall moving over the same areas
will have the potential to produce flash flooding.
+ Read More
You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued.
Updated: Apr 27, 1:40 PM Source: NWS Alert