A large upper-level ridge of high pressure centered over the Midwest brought very hot weather to central Illinois on August 26th and 27th. High temperatures were mostly in the lower to middle 90s on August 26th, but climbed into the 95-100 degree range on the 27th.
Every event with a place to put it; 21 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 centered over the Midwest brought very hot weather to central Illinois on August 26th and 27th. High temperatures were mostly in the lower to middle 90s on August 26th, but climbed into the 95-100 degree range on the 27th. With dewpoints hovering in the upper 70s to near 80 degrees, heat index readings peaked from 105 to 115 degrees along and north of the I-72 corridor during the afternoon of August 27th. While no heat-related deaths were reported, this was the hottest period of weather across central Illinois during the entire summer of 2024.
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 27, 9:11 AM CST, 49 minutes earlier. Its key messages:
Area Forecast Discussion...Updated National Weather Service Lincoln IL 1011 AM CDT Tue Aug 27 2024 .KEY MESSAGES... - Dangerous heat will continue across central Illinois today. Heat index readings may exceed 110 degrees along and north of I-72. - Scattered thunderstorms will develop this evening into tonight. A few of the storms could become strong to severe north of I-72...with the primary risk being damaging wind gusts. && .UPDATE... Issued at 1011 AM CDT Tue Aug 27 2024 14z/9am temperatures are running 2-4 degrees warmer than they were 24 hours ago. With full sunshine and continued southwesterly winds of around 10mph, it appears afternoon highs will top out in the middle to upper 90s. Dewpoints are currently highest along/west of I-55 where readings are mostly in the middle 70s. While some models suggest modest mixing of dewpoints into the upper 60s to around 70 degrees, think this is a bit overdone based on what was observed yesterday afternoon. Have therefore maintained lower to middle 70s dewpoints across all but the far E/SE CWA through the afternoon. This results in peak heat index values at or above 110 degrees along/north of a Rushville to Bloomington line...with readings up to 105 degrees as far south as I-70. Have therefore maintained current heat headlines with no modifications. Latest CAM guidance suggests widely scattered convection developing ahead of an approaching cold front across northern Missouri into central/eastern Iowa by late afternoon...with activity gradually spreading eastward into the Illinois River Valley this evening. SPC upgraded the Day 1 Convective Outlook to feature a Slight Risk for severe weather north of the I-72 corridor. While areal coverage of convection remains in question, think any severe risk will not materialize until after 8pm. Scattered damaging wind gusts will be the primary concern with any cells that fire later this evening into tonight. Barnes && .DISCUSSION... Issued at 251 AM CDT Tue Aug 27 2024 This morning, central Illinois falls beneath an anonymously strong 595+ dam H5 high which is acting as a pressure cooker over central Illinois. Yesterday temperatures were able to warm into the mid to upper 90s across central Illinois while dew points west of I-57 rose into the mid to upper 70s. Similar conditions are expected across the area today, warming a couple degrees more. The combination of dangerous heat and humidity will result in heat indices of 105-115 degrees this afternoon. An Excessive Heat Warning is in effect roughly along and north of I-72 while a Heat Advisory is in effect south. This evening, a damping upper level disturbance will move into the Great Lakes helping push the upper ridge slightly further south, while at the surface, a weak trough will sag south across the Upper Midwest and serve as the focus for thunderstorm development late this afternoon and evening, initially over Iowa and northern Illinois. 00Z GFS suggests that much of central and northern Illinois will have moderately strong instability with 2500-3000 J/kg MLCAPE. While deep layer shear is initially modest near the weak flow of the upper ridge, it is expected to increase enough as the ridge shifts south, enough to allow some organization of storms contributing to an attendant severe weather threat. Damaging wind gusts will be the primary concern. By Wednesday, upper ridge continues to get shunted further south while locally the remnants of the aforementioned surface trough linger over portions of central Illinois. Convective debris/outflow from the previous nights storms complicate the temperature forecast and add uncertainty on how high heat indices will get during the afternoon. HREF probabilities of reaching Heat Advisory criteria are low as a result, less than 20 percent. NBM mean peak heat index values generally peak in the 90s to low 100s across central Illinois. Given the uncertainties and potential marginal nature of the heat Wednesday, do no have plans at this time to extend heat headlines into the day, but one may eventually be needed, especially south of I-70. A stronger shortwave trough is progged to move along the US/Canadian border Thursday and Friday. Southwest flow will overspread central Illinois again Thursday and prolong the heat and humidity over the region, with conditions once again near criteria for heat headlines. As the shortwave lifts across Ontario to Hudson Bay Friday, it will push a cold front across the Midwest marking an end to the heat wave and bringing the next decent chance for widespread showers and storms. More seasonable conditions return to the area next weekend behind the front trending towards slightly below normal early next week with dry conditions favored as an expansive Canadian high builds into the region. Deubelbeiss && .AVIATION... (For the 12z TAFs through 12z Wednesday Morning) Issued at 553 AM CDT Tue Aug 27 2024 Light south to southwest flow around 10 kt or less and VFR conditions will prevail this morning and afternoon. Storms are expected to develop over Iowa and northern Illinois this evening, then move across portions of central Illinois late this evening and overnight. Uncertainty in the location and timing preclude more than a Prob30 mention in the forecast at this time. Deubelbeiss && .CLIMATE... Issued at 600 PM CDT Mon Aug 26 2024 Record & Forecast Highs for Tues Aug 27 Record | Forecast Peoria......... 98 in 1899 | 98 Lincoln........ 98 in 1936 | 97 Springfield.... 97 in 1983 | 97 Bloomington.... 102 in 1899 | 96 Decatur........ 101 in 1983 | 96 Champaign...... 96 in 1953 | 97 Mattoon........ 98 in 1953 | 95 Record Warm Lows & Forecast Lows for Tues Aug 27 Record | Forecast Peoria......... 78 in 1886 | 76 Lincoln........ 75 in 1921 | 73 Springfield.... 77 in 1936 | 76 Bloomington.... 75 in 1977 | 75 Decatur........ 76 in 2018 | 74 Champaign...... 73 in 2020* | 72 Mattoon........ 75 in 2004* | 71 * - occurred in several years, most recent shown. && .ILX WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM CDT this evening for ILZ027>031-036>038-040>051-053. Heat Advisory until 8 PM CDT this evening for ILZ052-054>057- 061>063-066>068-071>073. &&
Hazardous Weather Outlook National Weather Service Lincoln IL 422 AM CDT Tue Aug 27 2024 ILZ027>031-036>038-040>051-053-280930- Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler- Mason-Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard-Scott- Morgan-Sangamon-Macon- 422 AM CDT Tue Aug 27 2024 This Hazardous Weather Outlook is for central Illinois, east central Illinois and west central Illinois. .DAY ONE...Today and tonight. Dangerously hot and humid conditions are forecast today, with heat indices reaching 105 to 115 degrees. Scattered thunderstorms tonight will bring a level 1 of 5 (marginal) risk for severe weather from damaging wind gusts and large hail. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Heat indices are forecast to reach the upper 90s to nearly 105 both Wednesday and Thursday. Scattered thunderstorms will once again pose a level 1 of 5 (marginal) risk for severe weather from damaging wind gusts and large hail Wednesday. Additional thunderstorms will accompany a cold front late Thursday night into Friday. Severe potential with those storms is uncertain at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. ILZ052-054>057-061>063-066>068-071>073-280930- Christian-Moultrie-Douglas-Coles-Edgar-Shelby-Cumberland-Clark- Effingham-Jasper-Crawford-Clay-Richland-Lawrence- 422 AM CDT Tue Aug 27 2024 This Hazardous Weather Outlook is for central Illinois, east central Illinois and southeast Illinois. .DAY ONE...Today and tonight. Hot and humid conditions are forecast today, with heat indices reaching 100 to 110 degrees. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Hot and humid weather will persist through at least Thursday, with heat indices reaching the upper 90s to around 105 degrees both Wednesday and Thursday. Scattered thunderstorms will pose a level 1 of 5 (marginal) risk for severe weather from damaging wind gusts and large hail Wednesday. Additional thunderstorms will accompany a cold front Friday. Severe potential with those storms is uncertain at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. Bumgardner
The national radar mosaic for the moment the first event began.
21 excessive heat. Local standard time, as filed.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 105-110 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 105-110 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 115-120 degrees during the afternoon of August 27th...including 119 degrees at the Galesburg Airport. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th...including 111 degrees at the Lincoln Airport. No heat-related deaths were reported.
Heat index readings peaked at 105-110 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th...including 112 degrees at the Bloomington Airport. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th...including 114 degrees at the Peoria Airport. No heat-related deaths were reported.
Heat index readings peaked at 105-110 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th...including 111 degrees at the Springfield Airport. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 105-110 degrees during the afternoon of August 27th. No heat-related deaths were reported.
Heat index readings peaked at 110-115 degrees during the afternoon of August 27th. No heat-related deaths were reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2024Every state in 2024This day in weather historyWarnings in Illinois, August 2024
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: 1214393, 1214394, 1214395, 1214396, 1214397, 1214398, 1214400, 1214401, 1214402, 1214403, 1214404, 1214405, 1214407, 1214408, 1214409, 1214410, 1214411, 1214413, 1214414, 1214415, 1214416.