Alert archive / Missouri / Excessive Heat Warnings in 2021

Excessive Heat Warning 1, NWS St. Louis, MO

August 10, 2021Madison County, Saint Clair County, Illinois; Saint Charles County, Saint Louis County, City of Saint Louis, Missouri

NWS St. Louis, MO issued this excessive heat warning at Aug 10, 2021, 3:20 AM CDT for Madison County, Saint Clair County, Illinois; Saint Charles County, Saint Louis County, City of Saint Louis, Missouri. It took effect at Aug 10, 2021, 12:00 PM CDT. It was in force for 56 hr. 39 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Aug 10, 2021, 3:20 AM CDT (08:20 UTC)
In effect from
Aug 10, 2021, 12:00 PM CDT
Expired
Aug 12, 2021, 8:00 PM CDT
In force
56 hr
Issued by
NWS St. Louis, MO

Counties Madison County, IL, Saint Clair County, IL, City of Saint Louis, MO, Saint Charles County, MO, Saint Louis County, MO

The radar

The St Louis radar (KLSX), 39 km from the middle of the area, began a volume at 08:23 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 10, 12:55 PM CDTTSTM WND DMG2 Nne Maryland Heights, MO4 TO 8 INCH TREE LIMBS BROKEN OFF THE TOPS OF SOME BRADFORD PEAR TREES IN AN INDUSTRIAL AREA JUST SOUTH OF THE RIVERPORT AMPHITHEATRE. WIND SPEED IS UNKNOWN.
Aug 10, 1:35 PM CDTHAIL 0.251 W Mehlville, MO
Aug 10, 1:37 PM CDTHAIL 0.5Affton, MOHAIL WAS SPOTTY AND ESTIMATED SIZE WAS SLIGHTLY SMALLER THAN DIMES.
Aug 10, 1:40 PM CDTHAIL 0.51 Nne Mehlville, MOREPORT SUBMITTED VIA SOCIAL MEDIA.
Aug 10, 1:42 PM CDTHAIL 0.251 N Mehlville, MO
Aug 10, 2:05 PM CDTHAIL 0.75Caseyville, ILHAIL LASTED ABOUT 1 MINUTE.
Aug 12, 6:02 PM CDTTSTM WND DMG2 Ene Foristell, MOLARGE TREE BLOWN OVER ONTO W. MEYER ROAD IN WENTZVILLE.
Aug 12, 6:04 PM CDTTSTM WND DMG2 Wnw Wentzville, MOSEVERAL LARGE TREE BRANCHES DOWN.
Aug 12, 6:04 PM CDTTSTM WND DMGNew Melle, MOPORTION OF FLAT ROOF PEELED OFF OF ELEMENTARY SCHOOL
Aug 12, 6:04 PM CDTTSTM WND DMGNew Melle, MOPORTION OF FLAT ROOF PEELED OFF OF ELEMENTARY SCHOOL.
Aug 12, 6:04 PM CDTTSTM WND GST 52Flint Hill, MONEAR INTERSECTION OF US HIGHWAY 61 AND HIGHWAY P.
Aug 12, 6:05 PM CDTTSTM WND GST 642 Wsw Wentzville, MOMODOT OBSERVATION SITE ON INTERSTATE 70.
Aug 12, 6:14 PM CDTTSTM WND DMG2 E O'Fallon, MOSEVERAL TREES BLOWN DOWN NEAR INTERSECTION OF MEXICO ROAD AND BELLEAU CREEK ROAD.
Aug 12, 6:15 PM CDTTSTM WND DMG2 E Dardenne Prairie, MOSEVERAL TREES BLOWN DOWN NEAR INTERSECTION OF HIGHWAYS N AND K.
Aug 12, 6:21 PM CDTTSTM WND DMG1 Nne Defiance, MOTREE AND POWER LINE BLOWN DOWN OVER HIGHWAY DD NEAR INTERSECTION WITH HIGHWAY 94.
Aug 12, 6:25 PM CDTTSTM WND GST 564 Nw Clarkson Valley, MOMEASURED KSUS ASOS.
Aug 12, 6:29 PM CDTTSTM WND DMG1 Ene Eureka, MOSHINGLES BLOWN OFF OF A FEW HOUSES.
Aug 12, 6:34 PM CDTTSTM WND DMGFlorissant, MOLARGE LIMBS DOWN ON HOUSE.
Aug 12, 6:34 PM CDTTSTM WND GST 552 Ene Maryland Heights, MO
Aug 12, 6:37 PM CDTTSTM WND DMG1 N Kirkwood, MOSEVERAL TREES AND NUMEROUS TREE LIMBS WERE BLOWN DOWN NEAR THE INTERSECTION OF MANCHESTER ROAD AND GEYER ROAD.
Aug 12, 6:37 PM CDTTSTM WND DMGKirkwood, MOSEVERAL TREES AND NUMEROUS TREE LIMBS BLOWN DOWN NEAR THE INTERSECTION OF MANCHESTER ROAD AND GEYER ROAD.
Aug 12, 6:39 PM CDTTSTM WND GST 581 Wnw Berkeley, MOCORRECTS PREVIOUS TSTM WND GST REPORT FROM 1 WNW BERKELEY. WIND GUST REPORTED AT ST. LOUIS-LAMBERT INTERNATIONAL AIRPORT.
Aug 12, 6:41 PM CDTTSTM WND DMG1 Sse Webster Groves, MOTREE DOWN BLOCKING WATSON ROAD.
Aug 12, 6:41 PM CDTTSTM WND DMGBrentwood, MOLARGE TREE SNAPPED IN HALF CAUSING DAMAGE TO A HOUSE ON PINE AVENUE NEAR THE INTERSECTION WITH ST. CLAIR IN BRENTWOOD.
Aug 12, 6:42 PM CDTTSTM WND DMG1 Nw Shrewsbury, MOLARGE TREE LIMB BLOWN DOWN.
Aug 12, 6:42 PM CDTTSTM WND GST 581 Wnw Berkeley, MOWIND GUST REPORTED AT ST. LOUIS-LAMBERT INTERNATIONAL AIRPORT.
Aug 12, 6:51 PM CDTTSTM WND DMGOakville, MONUMEROUS TREE LIMBS BLOWN DOWN.
Aug 12, 6:54 PM CDTTSTM WND DMGGranite City, ILLARGE TREE BLOWN OVER ONTO ILLINOIS ROUTE 3.
Aug 12, 6:54 PM CDTTSTM WND DMGNormandy, MOLIMBS DOWN
Aug 12, 6:54 PM CDTTSTM WND DMGNormandy, MOLIMBS DOWN.
Aug 12, 6:55 PM CDTTSTM WND GST 581 Ssw Hazelwood, MO
Aug 12, 7:00 PM CDTTSTM WND DMGOakville, MOLARGE TREE LIMBS DOWN.
Aug 12, 7:01 PM CDTTSTM WND GST 671 Ese Sauget, IL
Aug 12, 7:01 PM CDTTSTM WND GST 671 Ne Cahokia, IL
Aug 12, 7:07 PM CDTTSTM WND DMG1 Ssw Collinsville, ILSEVERAL TREES BLOWN DOWN AROUND TOWN. ALSO, SEVERAL POWER LINES WERE BLOWN DOWN.
Aug 12, 7:10 PM CDTTSTM WND DMG2 Sse Belleville, ILVIA TWITTER PHOTO OF SMALL TREE UPROOTED AND MEDIUM SIZED TREE LIMB SNAPPED.
Aug 12, 7:10 PM CDTTSTM WND DMGMillstadt, ILNUMEROUS TREE LIMBS BLOWN DOWN. VIA FACEBOOK.
Aug 12, 7:20 PM CDTTSTM WND DMG3 Nnw Freeburg, ILPOWER LINES BLOWN DOWN AT THE INTERSECTION OF ILLINOIS ROUTE 15 AND JEFFERSON ROAD.
Aug 12, 7:22 PM CDTTSTM WND DMGFreeburg, ILNUMEROUS TREES AND TREE LIMBS BLOWN DOWN AROUND TOWN.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 8.3 hours before the alert went out and 216 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2021-08-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4598 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 00:00Z on 2021-08-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 179 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
4598 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
775 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
179 m²/s²
0-3 km storm-relative helicity
284 m²/s²
Significant tornado parameter
3.9
Supercell composite
24.2

Open this sounding in Storm Lab

The text

As transmitted.

834 
WWUS73 KLSX 100820
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service St Louis MO
320 AM CDT Tue Aug 10 2021

ILZ100-101-MOZ061-063-064-102330-
/O.UPG.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
/O.NEW.KLSX.EH.W.0001.210810T1700Z-210813T0100Z/
Madison IL-Saint Clair-Saint Charles MO-Saint Louis MO-Saint
Louis City MO-
Including the cities of Saint Charles, Cahokia, Alton, Saint
Louis, Belleville, and Edwardsville
320 AM CDT Tue Aug 10 2021

...EXCESSIVE HEAT WARNING IN EFFECT FROM NOON TODAY TO 8 PM CDT 
THURSDAY...

* WHAT...Dangerously hot conditions with heat index values up to 110 
  expected.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO and 
  Saint Louis MO Counties. In Illinois, Madison IL and Saint Clair 
  Counties.

* WHEN...From Noon today to 8 PM CDT Thursday.

* IMPACTS...Heat related illnesses increase significantly during 
  extreme heat and high humidity events.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ058-079-095>099-102-MOZ018-019-026-027-034>036-041-042-047>052-
059-060-062-065-072>075-084-085-099-102330-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Greene IL-Randolph IL-Adams IL-Brown IL-Pike IL-Calhoun IL-Jersey
IL-Monroe IL-Knox MO-Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls
MO-Pike MO-Boone MO-Audrain MO-Moniteau MO-Cole MO-Osage MO-
Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren MO-
Franklin MO-Jefferson MO-Crawford MO-Washington MO-Saint Francois
MO-Sainte Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Mount Sterling, Columbia, Quincy,
Pittsfield, Sparta, Union, Washington, Mexico, Bowling Green,
Jefferson City, Chester, Farmington, Sullivan, Hannibal, and
Fulton
320 AM CDT Tue Aug 10 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THURSDAY...

* WHAT...Heat index values up to 107.

* WHERE...Portions of southwest and west central Illinois. Portions 
  of central, east central, northeast, and southeast Missouri.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ059-060-064-065-069-070-074-102330-
/O.CON.KLSX.HT.Y.0004.210810T1700Z-210813T0100Z/
Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-Marion IL-
Washington IL-
Including the cities of Litchfield, Centralia, Salem, and
Vandalia
320 AM CDT Tue Aug 10 2021

...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 8 PM CDT 
THURSDAY...

* WHAT...Heat index values up to 108 expected.

* WHERE...Bond IL, Clinton IL, Fayette IL, Marion IL, Montgomery IL, 
  Washington IL and Macoupin IL Counties.

* WHEN...From Noon today to 8 PM CDT Thursday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

Glass
6 follow-up statements
278 
WWUS73 KLSX 102022
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service St Louis MO
322 PM CDT Tue Aug 10 2021

ILZ100-101-MOZ061-063-064-111130-
/O.CON.KLSX.EH.W.0001.000000T0000Z-210813T0100Z/
Madison IL-Saint Clair-Saint Charles MO-Saint Louis MO-Saint
Louis City MO-
Including the cities of Saint Charles, Cahokia, Alton, Saint
Louis, Belleville, and Edwardsville
322 PM CDT Tue Aug 10 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM CDT 
THURSDAY...

* WHAT...Dangerously hot conditions with heat index values up to 113.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO and 
  Saint Louis MO Counties. In Illinois, Madison IL and Saint Clair 
  Counties.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Heat related illnesses increase significantly during 
  extreme heat and high humidity events.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ058-079-095>099-102-MOZ018-019-026-027-034>036-041-042-047>052-
059-060-062-065-072>075-084-085-099-111130-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Greene IL-Randolph IL-Adams IL-Brown IL-Pike IL-Calhoun IL-Jersey
IL-Monroe IL-Knox MO-Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls
MO-Pike MO-Boone MO-Audrain MO-Moniteau MO-Cole MO-Osage MO-
Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren MO-
Franklin MO-Jefferson MO-Crawford MO-Washington MO-Saint Francois
MO-Sainte Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Mount Sterling, Columbia, Quincy,
Pittsfield, Sparta, Union, Washington, Mexico, Bowling Green,
Jefferson City, Chester, Farmington, Sullivan, Hannibal, and
Fulton
322 PM CDT Tue Aug 10 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THURSDAY...

* WHAT...Heat index values up to 110.

* WHERE...Portions of southwest and west central Illinois. Portions 
  of central, east central, northeast, and southeast Missouri.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ059-060-064-065-069-070-074-111130-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-Marion IL-
Washington IL-
Including the cities of Litchfield, Centralia, Salem, and
Vandalia
322 PM CDT Tue Aug 10 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THURSDAY...

* WHAT...Heat index values up to 112.

* WHERE...Bond IL, Clinton IL, Fayette IL, Marion IL, Montgomery IL, 
  Washington IL and Macoupin IL Counties.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

Pfahler
294 
WWUS73 KLSX 110839
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service St Louis MO
339 AM CDT Wed Aug 11 2021

ILZ100-101-MOZ061-063-064-112345-
/O.CON.KLSX.EH.W.0001.000000T0000Z-210813T0100Z/
Madison IL-Saint Clair-Saint Charles MO-Saint Louis MO-Saint
Louis City MO-
Including the cities of Saint Charles, Cahokia, Alton, Saint
Louis, Belleville, and Edwardsville
339 AM CDT Wed Aug 11 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM CDT 
THURSDAY...

* WHAT...Dangerously hot conditions with heat index values up to 110.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO and 
  Saint Louis MO Counties. In Illinois, Madison IL and Saint Clair 
  Counties.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Heat related illnesses increase significantly during 
  extreme heat and high humidity events.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ058-079-095>099-102-MOZ018-019-026-027-034>036-041-042-047>052-
059-060-062-065-072>075-084-085-099-112345-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Greene IL-Randolph IL-Adams IL-Brown IL-Pike IL-Calhoun IL-Jersey
IL-Monroe IL-Knox MO-Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls
MO-Pike MO-Boone MO-Audrain MO-Moniteau MO-Cole MO-Osage MO-
Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren MO-
Franklin MO-Jefferson MO-Crawford MO-Washington MO-Saint Francois
MO-Sainte Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Mount Sterling, Columbia, Quincy,
Pittsfield, Sparta, Union, Washington, Mexico, Bowling Green,
Jefferson City, Chester, Farmington, Sullivan, Hannibal, and
Fulton
339 AM CDT Wed Aug 11 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THURSDAY...

* WHAT...Heat index values up to 108.

* WHERE...Portions of southwest and west central Illinois. Portions 
  of central, east central, northeast, and southeast Missouri.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ059-060-064-065-069-070-074-112345-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-Marion IL-
Washington IL-
Including the cities of Litchfield, Centralia, Salem, and
Vandalia
339 AM CDT Wed Aug 11 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THURSDAY...

* WHAT...Heat index values up to 110.

* WHERE...Bond IL, Clinton IL, Fayette IL, Marion IL, Montgomery IL, 
  Washington IL and Macoupin IL Counties.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

Glass
549 
WWUS73 KLSX 111943
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service St Louis MO
243 PM CDT Wed Aug 11 2021

ILZ100-101-MOZ061-063-064-121045-
/O.CON.KLSX.EH.W.0001.000000T0000Z-210813T0100Z/
Madison IL-Saint Clair-Saint Charles MO-Saint Louis MO-Saint
Louis City MO-
Including the cities of Saint Charles, Cahokia, Alton, Saint
Louis, Belleville, and Edwardsville
243 PM CDT Wed Aug 11 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM CDT 
THURSDAY...

* WHAT...Dangerously hot conditions with heat index values up to 111.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO and 
  Saint Louis MO Counties. In Illinois, Madison IL and Saint Clair 
  Counties.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Heat related illnesses increase significantly during 
  extreme heat and high humidity events.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ058-079-095>099-102-MOZ018-019-026-027-034>036-041-042-047>052-
059-060-062-065-072>075-084-085-099-121045-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Greene IL-Randolph IL-Adams IL-Brown IL-Pike IL-Calhoun IL-Jersey
IL-Monroe IL-Knox MO-Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls
MO-Pike MO-Boone MO-Audrain MO-Moniteau MO-Cole MO-Osage MO-
Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren MO-
Franklin MO-Jefferson MO-Crawford MO-Washington MO-Saint Francois
MO-Sainte Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Mount Sterling, Columbia, Quincy,
Pittsfield, Sparta, Union, Washington, Mexico, Bowling Green,
Jefferson City, Chester, Farmington, Sullivan, Hannibal, and
Fulton
243 PM CDT Wed Aug 11 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THURSDAY...

* WHAT...Heat index values up to 108.

* WHERE...Portions of southwest and west central Illinois. Portions 
  of central, east central, northeast, and southeast Missouri.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ059-060-064-065-069-070-074-121045-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-Marion IL-
Washington IL-
Including the cities of Litchfield, Centralia, Salem, and
Vandalia
243 PM CDT Wed Aug 11 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THURSDAY...

* WHAT...Heat index values up to 110.

* WHERE...Bond IL, Clinton IL, Fayette IL, Marion IL, Montgomery IL, 
  Washington IL and Macoupin IL Counties.

* WHEN...Until 8 PM CDT Thursday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

Pfahler
195 
WWUS73 KLSX 120904
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service St Louis MO
404 AM CDT Thu Aug 12 2021

ILZ100-101-MOZ061-063-064-130015-
/O.CON.KLSX.EH.W.0001.000000T0000Z-210813T0100Z/
Madison IL-Saint Clair-Saint Charles MO-Saint Louis MO-Saint
Louis City MO-
Including the cities of Saint Charles, Cahokia, Alton, Saint
Louis, Belleville, and Edwardsville
404 AM CDT Thu Aug 12 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM CDT THIS 
EVENING...

* WHAT...Dangerously hot conditions with heat index values up to 110.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO and 
  Saint Louis MO Counties. In Illinois, Madison IL and Saint Clair 
  Counties.

* WHEN...Until 8 PM CDT this evening.

* IMPACTS...Heat related illnesses increase significantly during 
  extreme heat and high humidity events.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

Do not leave young children and pets in unattended vehicles. Car 
interiors will reach lethal temperatures in a matter of minutes.

&&

$$

ILZ058-079-095>099-102-MOZ018-019-026-027-034>036-041-042-047>052-
059-060-062-065-072>075-084-085-099-130015-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Greene IL-Randolph IL-Adams IL-Brown IL-Pike IL-Calhoun IL-Jersey
IL-Monroe IL-Knox MO-Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls
MO-Pike MO-Boone MO-Audrain MO-Moniteau MO-Cole MO-Osage MO-
Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren MO-
Franklin MO-Jefferson MO-Crawford MO-Washington MO-Saint Francois
MO-Sainte Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Mount Sterling, Columbia, Quincy,
Pittsfield, Sparta, Union, Washington, Mexico, Bowling Green,
Jefferson City, Chester, Farmington, Sullivan, Hannibal, and
Fulton
404 AM CDT Thu Aug 12 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THIS EVENING...

* WHAT...Heat index values up to 105.

* WHERE...Portions of southwest and west central Illinois. Portions 
  of central, east central, northeast, and southeast Missouri.

* WHEN...Until 8 PM CDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ059-060-064-065-069-070-074-130015-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-Marion IL-
Washington IL-
Including the cities of Litchfield, Centralia, Salem, and
Vandalia
404 AM CDT Thu Aug 12 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THIS EVENING...

* WHAT...Heat index values up to 108.

* WHERE...Bond IL, Clinton IL, Fayette IL, Marion IL, Montgomery IL, 
  Washington IL and Macoupin IL Counties.

* WHEN...Until 8 PM CDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

Glass
609 
WWUS73 KLSX 121956
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service St Louis MO
256 PM CDT Thu Aug 12 2021

ILZ095-096-MOZ018-019-026-027-122100-
/O.CAN.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Adams IL-Brown IL-Knox MO-Lewis MO-Shelby MO-Marion MO-
Including the cities of Hannibal, Mount Sterling, and Quincy
256 PM CDT Thu Aug 12 2021

...HEAT ADVISORY IS CANCELLED...

Showers and thunderstorms have significantly cooled temperatures 
this afternoon across the area. Therefore, heat index values are no 
longer expected to reach dangerous levels.

$$

ILZ100-101-MOZ061-063-064-130100-
/O.CON.KLSX.EH.W.0001.000000T0000Z-210813T0100Z/
Madison IL-Saint Clair-Saint Charles MO-Saint Louis MO-Saint
Louis City MO-
Including the cities of Saint Charles, Cahokia, Alton, Saint
Louis, Belleville, and Edwardsville
256 PM CDT Thu Aug 12 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM CDT THIS 
EVENING...

* WHAT...Dangerously hot conditions with heat index values up to 107.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO and 
  Saint Louis MO Counties. In Illinois, Madison IL and Saint Clair 
  Counties.

* WHEN...Until 8 PM CDT this evening.

* IMPACTS...Heat related illnesses increase significantly during 
  extreme heat and high humidity events.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

Do not leave young children and pets in unattended vehicles. Car 
interiors will reach lethal temperatures in a matter of minutes.

&&

$$

ILZ058-079-097>099-102-MOZ034>036-041-042-047>052-059-060-062-065-
072>075-084-085-099-130100-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Greene IL-Randolph IL-Pike IL-Calhoun IL-Jersey IL-Monroe IL-
Monroe MO-Ralls MO-Pike MO-Boone MO-Audrain MO-Moniteau MO-Cole
MO-Osage MO-Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-
Warren MO-Franklin MO-Jefferson MO-Crawford MO-Washington MO-
Saint Francois MO-Sainte Genevieve MO-Iron MO-Madison MO-Reynolds
MO-
Including the cities of Columbia, Pittsfield, Mexico, Union,
Washington, Sparta, Bowling Green, Jefferson City, Chester,
Farmington, Sullivan, and Fulton
256 PM CDT Thu Aug 12 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THIS EVENING...

* WHAT...Heat index values up to 105.

* WHERE...Portions of southwest and west central Illinois. Portions 
  of central, east central, northeast, and southeast Missouri.

* WHEN...Until 8 PM CDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

ILZ059-060-064-065-069-070-074-130100-
/O.CON.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-Marion IL-
Washington IL-
Including the cities of Litchfield, Centralia, Salem, and
Vandalia
256 PM CDT Thu Aug 12 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THIS EVENING...

* WHAT...Heat index values up to 106.

* WHERE...Bond IL, Clinton IL, Fayette IL, Marion IL, Montgomery IL, 
  Washington IL and Macoupin IL Counties.

* WHEN...Until 8 PM CDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of 
the sun, and check up on relatives and neighbors.

&&

$$

Pfahler
321 
WWUS73 KLSX 130054
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service St Louis MO
754 PM CDT Thu Aug 12 2021

ILZ100-101-MOZ061-063-064-130200-
/O.EXP.KLSX.EH.W.0001.000000T0000Z-210813T0100Z/
Madison IL-Saint Clair-Saint Charles MO-Saint Louis MO-Saint
Louis City MO-
Including the cities of Saint Charles, Cahokia, Alton, Saint
Louis, Belleville, and Edwardsville
754 PM CDT Thu Aug 12 2021

...EXCESSIVE HEAT WARNING WILL EXPIRE AT 8 PM CDT THIS EVENING...

Cooler air has moved into the region ending the dangerous heat.

$$

ILZ058>060-064-065-069-070-074-079-097>099-102-MOZ034>036-041-042-
047>052-059-060-062-065-072>075-084-085-099-130200-
/O.EXP.KLSX.HT.Y.0004.000000T0000Z-210813T0100Z/
Greene IL-Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-
Marion IL-Washington IL-Randolph IL-Pike IL-Calhoun IL-Jersey IL-
Monroe IL-Monroe MO-Ralls MO-Pike MO-Boone MO-Audrain MO-Moniteau
MO-Cole MO-Osage MO-Callaway MO-Montgomery MO-Lincoln MO-
Gasconade MO-Warren MO-Franklin MO-Jefferson MO-Crawford MO-
Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO-
Madison MO-Reynolds MO-
Including the cities of Columbia, Pittsfield, Sparta, Litchfield,
Washington, Mexico, Bowling Green, Centralia, Jefferson City,
Salem, Chester, Union, Farmington, Sullivan, Vandalia, and Fulton
754 PM CDT Thu Aug 12 2021

...HEAT ADVISORY WILL EXPIRE AT 8 PM CDT THIS EVENING...

Cooler air has moved into the region ending the dangerous heat.

$$

Britt

The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 10, 3:38 AM CDTFlash Flood WarningLSXReynolds3 hr

Nearby

Excessive Heat Warnings in Missouri, 2021Excessive Heat Warnings in Illinois, 2021Every excessive heat warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.