S. produced an extended period of hot and humid weather across central Illinois from August 9th through August 14th.
Every event with a place to put it; 35 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS ILX wrote it up.
A large upper-level ridge of high pressure over the southern U.S. produced an extended period of hot and humid weather across central Illinois from August 9th through August 14th. With actual air temperatures well into the 90s and dewpoints in the upper 70s...heat index values soared above 105 degrees....with readings occasionally in excess of 110 degrees along and south of a Shelbyville to Paris line.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Lincoln, IL wrote its last area forecast discussion before the first event at Aug 9, 11:49 AM CST, 11 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1249 PM CDT MON AUG 9 2010 .DISCUSSION... ISSUED 1045 AM CDT MON AUG 9 2010 FORECAST WAS UPDATED AROUND DAWN TO INCREASE CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE IL RIVER VALLEY. UPDATING THE FORECAST AT MID MORNING TO REDUCE THE CHANCES OF SHOWERS AND THUNDERSTORMS OVER THE IL RIVER VALLEY WITH THE MCS AND ASSOCIATED CONVECTION WEAKENING AS IT MOVES SE ACROSS THE IL RIVER VALLEY. MAINTAINED HEAT HEADLINES WITH HEAT ADVISORY THROUGH TUE EARLY EVENING SW OF I-74 AND EXCESSIVE HEAT WARNING THROUGH THU EARLY EVENING ALONG AND SW OF A RUSHVILLE TO SPRINGFIELD TO SHELBYVILLE TO ROBINSON LINE. RADAR MOSAIC SHOWS SHOWERS AND ISOLATED THUNDERSTORMS WEAKENING AS THEY ARE MOVING SE TOWARD A RUSHVILLE TO BLOOMINGTON LINE AT 1030 AM. CANOPY OF MID/HIGH CLOUDS FROM MCS NORTH OF I-70 SHOULD BREAK UP TOO THIS AFTERNOON ALLOWING SUNSHINE TO HEAT UP TROPICAL AIR MASS WITH DEWPOINTS IN THE LOW TO MID 70S. HIGHS BY LATE AFTERNOON SHOULD REACH AROUND 90F FROM I-74 NORTH AND MID 90S SW AREAS. HEAT INDICES SHOULD REACH UPPER 90S FROM I-74 NE THIS AFTERNOON AND 100-105 DEGREES SW OF I-74. SHORT RANGE MODELS HAVE WEAK HIGH PRESSURE 1019 MB OVER THE MID ATLANTIC STATES WHILE FRONTAL BOUNDARY FROM NW WI INTO CENTRAL KS TO KEEP IL IN A SOUTHERLY TROPICAL FLOW. ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP THIS AFTERNOON MAINLY OVER THE IL RIVER VALLEY WITH SLIGHT RISK OF SEVERE STORMS AND HEAVY RAINS NW OF GALESBURG THIS AFTERNOON AND TONIGHT. ANOTHER MCS TO DEVELOP OVER NORTHERN IA/SOUTHERN MN TONIGHT AND MOVE EAST INTO NORTHERN IL TUE MORNING KEEPING MOST OF ITS CONVECTION NORTH OF CENTRAL IL. HUETTL && .AVIATION... ISSUED 1245 PM CDT MON AUG 9 2010 STRONG SUBTROPICAL HIGH PRESSURE RIDGE OF 595 DM AT 500 MB OVER TN TO REMAIN IN PLACE THROUGH TUE AND BRING ANOTHER HEAT WAVE TO CENTRAL IL THIS WEEK. MCS DISSIPATING OVER CENTRAL IL EARLY THIS AFTEROON LEAVING A FEW CUMULUS CLOUDS AND BROKEN CIRRUS CLOUDS. ISOLATED SHOWERS AND THUNDERSTORMS COULD DEVELOP DURING MID/LATE AFTERNOON AND DISSIPATE BY SUNSET IN THE TROPICAL AIR MASS WITH DEWPOINTS IN THE 70S ESPECIALLY FROM I-74 NORTH WHERE PUT VCTS FROM 20Z-24Z (3-7 PM). ANOTHER MCS TO DEVELOP ON NOSE OF LOW LEVEL JET OVER NORTHERN IA/SOUTHERN MN TONIGHT AND MOVE EAST ACROSS NORTHERN IL. SOUTHERN EXTENT OF CONVECTION FROM THIS MCS COULD REACH I-74 LATE TONIGHT/TUE MORNING ESPECIALLY BY PIA WHERE HAVE VCTS. MVFR VISIBILITIES OF 4-5 MILES FROM LIGHT FOG/HAZE POSSIBLE LATE TONIGHT/EARLY TUE MORNING. SSE WINDS OF 4-8 KTS PREVAIL THROUGH TUE MORNING WITH HIGH PRESSURE ANCHORED OVER THE ATLANTIC STATES AND A FRONTAL BOUNDARY FROM THE CENTRAL PLAINS INTO THE GREAT LAKES REGION. HUETTL && .PREV DISCUSSION... ISSUED 255 AM CDT MON AUG 9 2010 SHORT TERM...TODAY THROUGH WEDNESDAY MCS CURRENTLY ACROSS IOWA WILL TRACK EASTWARD INTO NORTH-CENTRAL ILLINOIS EARLY THIS MORNING...GENERALLY REMAINING ALONG AND NORTH OF A RUSHVILLE TO BLOOMINGTON-NORMAL LINE. COMPLEX IS MOVING INTO AN INCREASINGLY STABLE ENVIRONMENT...SO EXPECT STORMS TO WEAKEN AS THEY PUSH ACROSS THE MISSISSIPPI RIVER INTO THE NORTHWEST KILX CWA. WILL INCLUDE A PRE-FIRST PERIOD GROUPING FOR THE 4 AM ZONE ISSUANCE TO CARRY LIKELY POPS FROM PEORIA NORTHWARD THROUGH 12Z. AFTER THAT...STORMS WILL RAPIDLY DISSIPATE AFTER SUNRISE AS THEY OUTRUN BEST LOW-LEVEL INFLOW FOCUSED ACROSS EASTERN NEBRASKA/WESTERN IOWA. THE BIG QUESTION FOR THE REMAINDER OF THE DAY WILL BE WHERE THE RESULTING OUTFLOW BOUNDARY WILL EVENTUALLY LAY OUT. BASED ON EXPECTED TRAJECTORY OF EARLY MORNING MCS...THINK OUTFLOW WILL REACH THE I-72 CORRIDOR BEFORE MIXING BACK NORTHWARD DURING THE AFTERNOON. WITH UPPER RIDGE BUILDING NORTHWARD...AREAL COVERAGE WILL LIKELY BE LIMITED. WILL CARRY LOW CHANCE POPS ACROSS THE FAR NORTH IN CLOSER PROXIMITY TO EXPECTED POSITION OF BOUNDARY...WITH SLIGHT CHANCE POPS FURTHER SOUTH TO A JACKSONVILLE TO DANVILLE LINE. HIGH TEMPERATURES WILL MAINLY BE IN THE LOWER TO MIDDLE 90S...BUT MAY BE HELD IN THE UPPER 80S BEHIND THE OUTFLOW ACROSS KNOX...STARK...AND MARSHALL COUNTIES. AFTERNOON HEAT INDEX READINGS WILL EXCEED 100 DEGREES ACROSS THE CENTRAL AND SOUTHERN ZONES WHERE HEAT ADVISORIES AND EXCESSIVE HEAT WARNINGS ARE CURRENTLY IN EFFECT. SYNOPTIC PATTERN WILL REMAIN UNCHANGED TONIGHT...AS CENTER OF UPPER RIDGE MOVES INTO THE LOWER OHIO RIVER VALLEY. WITH HIGHER HEIGHTS IN PLACE ACROSS THE REGION...NOCTURNAL CONVECTION WILL LIKELY DEVELOP A BIT FURTHER NORTH THAN LAST NIGHT. MODELS ARE INDICATING A WEAKER LOW-LEVEL JET FOCUSED ON NORTHERN IOWA INTO SOUTHERN WISCONSIN. WITH THAT SAID...AM NOT COMFORTABLE GOING WITH A COMPLETELY DRY FORECAST...ESPECIALLY GIVEN MESOSCALE MODE OF FORCING. WILL THEREFORE CARRY SLIGHT CHANCE POPS FROM PEORIA NORTHWARD IN CASE CONVECTION FIRES FURTHER SOUTH THAN EXPECTED. ANOTHER HOT AND VERY HUMID DAY WILL BE IN STORE FOR TUESDAY...AS UPPER HIGH REMAINS IN PLACE JUST TO THE SOUTH OF ILLINOIS. WITH INCREASINGLY MOIST LOW-LEVEL ENVIRONMENT ADVECTING INTO THE REGION...WIDELY SCATTERED THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON...PARTICULARLY ACROSS THE WESTERN HALF OF THE CWA. UPPER HIGH WILL BEGIN TO RETROGRADE WESTWARD INTO THE SOUTHERN PLAINS ON WEDNESDAY...AS NORTHERN STREAM WAVE TRACKS THROUGH THE NORTHERN PLAINS TOWARD THE GREAT LAKES. THIS WILL PUSH A COLD FRONT SOUTHWARD INTO CENTRAL ILLINOIS LATE WEDNESDAY INTO THURSDAY. MODELS REMAIN IN GOOD AGREEMENT WITH THE TIMING OF FROPA...SO WILL MAINTAIN LOW CHANCE POPS ACROSS THE BOARD WEDNESDAY AND WEDNESDAY NIGHT AS THE BOUNDARY PUSHES THROUGH. LONG TERM...THURSDAY THROUGH SUNDAY SLIGHTLY COOLER AND LESS HUMID CONDITIONS APPEAR ON TAP FOR THE END OF THE WEEK...AS UPPER FLOW BECOMES W/NW. HIGH TEMPS WILL DROP BACK INTO THE UPPER 80S AND LOWER 90S ACROSS MOST LOCATIONS. NEXT COLD FRONT STILL APPEARS TO BE ON TARGET FOR SATURDAY...BUT WILL ONLY CARRY SLIGHT CHANCE POPS AT THIS TIME UNTIL EXACT TIMING BECOMES BETTER DEFINED. && .ILX WATCHES/WARNINGS/ADVISORIES... EXCESSIVE HEAT WARNING UNTIL 8 PM CDT THURSDAY FOR ILZ040- 047>052-061-066>068-071>073. HEAT ADVISORY UNTIL 8 PM CDT TUESDAY FOR ILZ036-041>044-053>057- 062-063. && BARNES
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LINCOLN IL 1035 AM CDT MON AUG 9 2010 ILZ036-041>044-053>057-062-063-101200- CLARK-COLES-CUMBERLAND-DE WITT-DOUGLAS-EDGAR-FULTON-LOGAN-MACON- MASON-MOULTRIE-PIATT- 1035 AM CDT MON AUG 9 2010 ...HEAT ADVISORY IN EFFECT UNTIL 8 PM CDT TUESDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS AND EAST CENTRAL ILLINOIS. .DAY ONE...TODAY AND TONIGHT HIGH TEMPERATURES AND INCREASING HUMIDITY WILL RESULT IN HEAT INDICES EXCEEDING THE 100 DEGREE MARK TODAY. REMNANT CLOUD COVER FROM OVERNIGHT CONVECTION TO THE NORTHWEST COULD KEEP THE TEMPERATURES IN CONTROL SOMEWHAT FOR A WHILE THIS MORNING...BUT SHOULD REBOUND QUICKLY WHEN THE SUN FINALLY DOMINATES IN THE AFTERNOON. THERE IS A CHANCE OF THUNDERSTORMS TODAY ACROSS THE ILLINOIS RIVER VALLEY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY ANOTHER HEAT WAVE IS EXPECTED MUCH OF THIS WEEK...SIMILAR TO THE HEAT AND HUMIDITY OF A FEW DAYS AGO. MANY AREAS WILL SEE AFTERNOON AND EARLY EVENING HEAT INDEX VALUES OF 100 TO 105 DEGREES...BEING THE HIGHEST ON TUESDAY AFTERNOON. THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY AND WEDNESDAY NIGHT. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT. ILZ040-047>052-061-066>068-071>073-101200- CASS-CHRISTIAN-CLAY-CRAWFORD-EFFINGHAM-JASPER-LAWRENCE-MENARD- MORGAN-RICHLAND-SANGAMON-SCHUYLER-SCOTT-SHELBY- 1035 AM CDT MON AUG 9 2010 ...EXCESSIVE HEAT WARNING IN EFFECT UNTIL 8 PM CDT THURSDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS AND SOUTHEAST ILLINOIS. .DAY ONE...TODAY AND TONIGHT HIGH TEMPERATURES AND INCREASING HUMIDITY WILL RESULT IN HEAT INDICES FROM 100 TO 105 DEGREES TODAY. REMNANT CLOUD COVER FROM OVERNIGHT CONVECTION TO THE NORTHWEST COULD KEEP THE TEMPERATURES IN CONTROL SOMEWHAT FOR A WHILE THIS MORNING...BUT SHOULD REBOUND QUICKLY WHEN THE SUN FINALLY DOMINATES IN THE HEAT OF THE AFTERNOON. THERE IS A CHANCE OF THUNDERSTORMS TODAY ACROSS THE ILLINOIS RIVER VALLEY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY ANOTHER HEAT WAVE IS EXPECTED MUCH OF THIS WEEK...SIMILAR TO THE HEAT AND HUMIDITY OF A FEW DAYS AGO. MANY AREAS WILL SEE AFTERNOON AND EARLY EVENING HEAT INDEX VALUES OF 100 TO 110 DEGREES...BEING THE HIGHEST TUESDAY AFTERNOON. THIS HEAT WAVE COULD LINGER INTO FRIDAY AFTERNOON IN SOUTHEAST ILLINOIS...WITH HEAT INDICES AROUND 100 DEGREES SOUTHEAST OF I-70. THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY AND WEDNESDAY NIGHT. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT. ILZ027>031-037-038-045-046-101200- CHAMPAIGN-KNOX-MARSHALL-MCLEAN-PEORIA-STARK-TAZEWELL-VERMILION- WOODFORD- 1035 AM CDT MON AUG 9 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL ILLINOIS AND EAST CENTRAL ILLINOIS. .DAY ONE...TODAY AND TONIGHT HEAT INDICES WILL REACH BETWEEN 95 AND 100 DEGREES THIS AFTERNOON. THERE IS A CHANCE OF THUNDERSTORMS ACROSS THE ILLINOIS RIVER VALLEY TODAY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY ANOTHER HEAT WAVE IS EXPECTED THROUGH AT LEAST THURSDAY...SIMILAR TO THE HEAT AND HUMIDITY OF A FEW DAYS AGO. THE MOST OPPRESSIVE PERIOD IS EXPECTED TO TUESDAY AFTERNOON AND EARLY EVENING...WHEN MANY AREAS WILL SEE HEAT INDEX VALUES OF 100 TO 105 DEGREES. THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY AND WEDNESDAY NIGHT. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT. KH
The national radar mosaic for the moment the first event began.
35 excessive heat. Local standard time, as filed.
Heat index readings exceeded 105 degrees across Schuyler County.
Heat index readings exceeded 105 degrees across Cass County.
Heat index readings exceeded 105 degrees across Scott County.
Heat index readings exceeded 105 degrees across Morgan County.
Heat index readings exceeded 105 degrees across Menard County.
Heat index readings exceeded 105 degrees across Sangamon County.
Heat index readings exceeded 105 degrees across Christian County.
Heat index readings exceeded 105 degrees across Shelby County.
Heat index readings exceeded 105 degrees across Effingham County.
Heat index readings exceeded 105 degrees across Jasper County.
Heat index readings exceeded 105 degrees across Crawford County.
Heat index readings exceeded 105 degrees across Clay County.
Heat index readings exceeded 105 degrees across Richland County.
Heat index readings exceeded 105 degrees across Lawrence County.
Heat index readings exceeded 105 degrees across Logan County.
Heat index readings exceeded 105 degrees across Macon County.
Heat index readings exceeded 105 degrees across Moultrie County.
Heat index readings exceeded 105 degrees across Douglas County.
Heat index readings exceeded 105 degrees across Coles County.
Heat index readings exceeded 105 degrees across Cumberland County.
Heat index readings exceeded 105 degrees across Edgar County.
Heat index readings exceeded 105 degrees across Clark County.
Heat index readings exceeded 105 degrees across DeWitt County.
Heat index readings exceeded 105 degrees across Piatt County.
Heat index readings exceeded 105 degrees across Champaign County.
Heat index readings exceeded 105 degrees across Vermilion County.
Heat index readings exceeded 105 degrees across Fulton County.
Heat index readings exceeded 105 degrees across Mason County.
Heat index readings exceeded 105 degrees across Tazewell County.
Heat index readings exceeded 105 degrees across McLean County.
Heat index readings exceeded 105 degrees across Woodford County.
Heat index readings exceeded 105 degrees across Marshall County.
Heat index readings exceeded 105 degrees across Stark County.
Heat index readings exceeded 105 degrees across Peoria County.
Heat index readings exceeded 105 degrees across Knox County.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2010Every state in 2010This day in weather historyWarnings in Illinois, August 2010
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 258157, 258158, 258159, 258160, 258161, 258162, 258163, 258164, 258165, 258166, 258167, 258168, 258169, 258170, 258171, 258172, 258173, 258174, 258175, 258176, 258177, 258178, 258179, 258180, 258181, 258182, 258183, 258184, 258185, 258186, 258187, 258188, 258189, 258190, 258191.