An upper-level ridge of high pressure over the Midwest brought a period of hot and very humid weather to central Illinois in mid to late July. while surface dewpoints in the upper 70s to around 80 degrees led to peak afternoon heat index readings in the 105-110 degree range.
Every event with a place to put it; 1 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.
An upper-level ridge of high pressure over the Midwest brought a period of hot and very humid weather to central Illinois in mid to late July. High temperatures on July 23rd reached the lower 90s...while surface dewpoints in the upper 70s to around 80 degrees led to peak afternoon heat index readings in the 105-110 degree range. A 61-year old man died of hyperthermia in Peoria during the afternoon of the 23rd while heat index values reached a maximum of 107 degrees at the Peoria Airport.
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 Jul 23, 4:02 AM CST, 4 hours 58 minutes earlier. Its key messages:
Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 502 AM CDT Wed Jul 23 2025 .KEY MESSAGES... - Confidence remains high (70-80%) that afternoon heat indices climb to 105 to 110 (locally higher) today and tomorrow. Readings will only fall into the upper 70s tonight. - Thunderstorm chances (30-50%) will exist Thursday evening into Saturday. There is a low (5%) risk for severe weather Thursday evening into Thursday night, mainly from strong winds. Meanwhile, heavy rain leading to localized flooding is the bigger concern overnight both Thursday and Friday nights. - Heat will ease slightly Friday into Saturday. However, a return to oppressive heat and humidity is anticipated Sunday into at least Monday, with a 50-70% chance for heat indices over 105 both days. && .DISCUSSION... Issued at 147 AM CDT Wed Jul 23 2025 ***** HOT AND HUMID TODAY, TOMORROW ***** At 130am, dewpoints and temperatures across central and southeast IL were in the mid and upper 70s, respectively, while skies were mostly clear under the influence of subsidence from an incoming ridge of high pressure. That ridge is expected to expand northward today, with LREF mean bringing 500mb heights to ~594 dam, allowing temperatures to climb into the low to mid 90s. In response, transpiration from (near) mature crops will induce a surge in dewpoints with values reaching the 77-80 degree range this afternoon; the combination of high temperatures and humidity will result in heat indices of 105-110 (locally higher). Now, the NAMNest, ARW, and NSSL depict a few storms firing with a subtle wave of vorticity aloft mid to late afternoon, so we have added slight chance (15-20%) PoPs to account for this. This may also lower our max heat indices in some spots today, particularly if the storms form early enough. Fortunately, wind shear (like forcing) is weak, so even if these storms develop they should not become organized, although with such high CAPE (NAM has 4500-5000 J/kg) values and mid level dry air evident on soundings we can't rule out a localized damaging wind gust from a wet microburst. Tomorrow, uncertainty increases a little more in the magnitude of afternoon heat indices as the ridge axis shifts east and the CAMs generally depict convection decaying at our doorstop in the early morning. Depending on how far east any outflow boundaries push into our area, and how many remnant clouds are in place, we may have lower heat indices compared to today or... we could have higher heat indices, especially with moisture pooling ahead of any boundary. In either case, it will still be hot during the afternoon with HREF suggesting a 60-90% chance for max heat indices over 105 - highest east. ***** STORM CHANCES THURSDAY EVENING THROUGH SATURDAY ***** A shortwave trough will attempt to flatten the ridge tomorrow evening, leading to thunderstorm development across Iowa, Wisconsin, and perhaps northern Illinois. According to the GFS, 0-6km bulk shear vectors will be oriented roughly west-southwest to east- northeast, and the shortwave trough (and attendant increase in shear) will take its time sinking into our area - suggesting the the best opportunity for storms would be overnight into early Friday morning. However, the 00z HRRR is a bit farther south, having storms impacting much of our CWA after 4pm tomorrow. The severe risk would certainly be higher with the HRRR's earlier timing solution, given higher diurnally driven instability (though only 20-30 kt EBWD would suggest organization and hence severe risk would be limited). However, in either case, storms may generate heavy rain given the 2- 2.2 inch PWATs, ~13kft deep warm cloud layer, and moderate-strong moisture transport via the LLJ. WPC is forecasting a slight (level 2 of 4) risk for excessive rainfall tomorrow evening into tomorrow night. In the wake of those storms and as the ridge weakens, Friday is looking a bit less hot with forecast highs in the mid to upper 80s. Uncertainty remains with whether more storms will fire on any remnant outflows during the afternoon, but another shortwave Friday night into Saturday morning should bring more storms into the area, with higher forecast shear compared with tomorrow night's activity. This may lead to some low severe weather risk, but our concern is higher for heavy rain, especially if we get a lot of rain tomorrow night into Friday morning which would saturate the ground and lower the precip threshold for flooding in spots. Like with Friday, additional storms may form on outflows Saturday afternoon, but chances will be slowly decreasing as subsidence returns with the ridge beginning to build back in late in the day. Given cloud cover and potential precip, Saturday is looking similar to Friday in terms of highs, with mid to upper 80s in our current forecast. ***** OPPRESSIVE HEAT RETURNS ***** Global models and their respective ensembles are in agreement the ridge strengthens over the Great Plains over the weekend and expands back into the Midwest Sunday into Monday. Consequently, heat and humidity will return to the area, and given some of the recent iterations of both the deterministic GFS and ECMWF there is some concern this could be just as oppressive or even more intense than our current heatwave, and receive less attention initially (because we've got heat and storms in the nearer term). Of course, a lot can change between now and then, especially considering our position on the ridge's northeast periphery in the "ring of fire" where storms, along with their outflows and associated clouds, may cause forecast high temperatures to bust. We'll continue to monitor, but at this point suspect heat headlines will return. Now, both as the ridge is building in Sunday-Monday and as it's breaking down (Tuesday or beyond), we'll need to keep an eye out for strong storms. Various runs of the deterministic ECMWF and GFS have hinted at one or more MCSs diving southeast through the Midwest and/or Great Lakes Sunday into Monday, and while for the most part this has been advertised to our north where shear is more favorable and capping is weaker or absent, high to extreme instability puts us in a precarious position...not to mention, the subtle mesoscale features dictating the path of these complexes are often poorly resolved by models, especially global models. Whenever the ridge breaks down and a front sinks into our area, probably Tuesday or later, we may wind up with some stronger storms as well. We'll continue to monitor and message changes in confidence in each of these scenarios. Bumgardner && .AVIATION... (For the 12z TAFs through 12z Thursday Morning) Issued at 458 AM CDT Wed Jul 23 2025 VFR flight conditions are expected to be predominant throughout the forecast period, though TEMPO groups were maintained for the 15-17z (10am-noon) period when diurnal cu may become widespread enough to form broken ceilings. Also, there may be brief visibility reductions this morning in widely isolated (10% coverage) showers, the strongest of which might be capable of a lightning strike or two given 1000-2000 MLCAPE from the latest RAP mesoanalysis. PROB30 groups were added to PIA and SPI to account for this potential. In addition, the PROB30 groups for this afternoon were maintained given lack of confidence that there won't be storms at the terminals as a subtle disturbance attempts to spark a few updrafts between 18-22z (1-5pm). For what it's worth, the NAMNest, which captured the morning storms, has backed off on the afternoon activity except at DEC and CMI. We'll allow the next shift to assess whether confidence in convection is low enough to remove the PROB30 groups at any of the terminals. Winds will blow from the south around 7-11 kt throughout the period. Bumgardner && .ILX WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 10 AM this morning to 7 PM CDT Thursday for ILZ027>031-036>038-040>057-061>063-066>068-071>073. &&
Hazardous Weather Outlook National Weather Service Lincoln IL 523 AM CDT Wed Jul 23 2025 ILZ027>031-036>038-241100- Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean- 523 AM CDT Wed Jul 23 2025 This Hazardous Weather Outlook is for central Illinois and west central Illinois. .DAY ONE...Today and tonight. Dangerously hot conditions are expected today. Heat index values of 105 to 110 degrees are likely. Isolated thunderstorms are possible this afternoon, with a threat of lightning, locally heavy rain, and gusty winds. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions are expected Thursday, with heat index values of 105 to 110 degrees likely. Additional triple digit heat index values are expected this weekend into early next week. Scattered thunderstorms are expected from Thursday evening through Saturday. Areas of heavy rain are possible. Strong to severe thunderstorms are possible Thursday evening, with a threat of locally damaging winds over 60 mph. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. ILZ040>057-061-241100- Schuyler-Mason-Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard- Scott-Morgan-Sangamon-Christian-Macon-Moultrie-Douglas-Coles-Edgar- Shelby- 523 AM CDT Wed Jul 23 2025 This Hazardous Weather Outlook is for central Illinois, east central Illinois and west central Illinois. .DAY ONE...Today and tonight. Dangerously hot conditions are expected today. Heat index values of 105 to 110 degrees are likely. Isolated thunderstorms are possible this afternoon, with a threat of lightning, locally heavy rain, and gusty winds. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions are expected Thursday, with heat index values of 105 to 110 degrees likely. Additional triple digit heat index values are expected this weekend into early next week. Scattered thunderstorms are expected from Thursday night through Saturday. While the severe weather threat appears low at this time, areas of heavy rain are possible. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. ILZ062-063-066>068-071>073-241100- Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence- 523 AM CDT Wed Jul 23 2025 This Hazardous Weather Outlook is for east central Illinois and southeast Illinois. .DAY ONE...Today and tonight. Dangerously hot conditions are expected today. Heat index values of 105 to 110 degrees are likely. Isolated thunderstorms are possible this afternoon, with a threat of lightning, locally heavy rain, and gusty winds. Minor flooding will continue on the Little Wabash River near Clay City. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions are likely much of this period, with peak heat index values of 105 to 110 degrees common. Scattered thunderstorms are expected from Thursday night through Saturday. While the severe weather threat appears low at this time, areas of heavy rain are possible. Minor flooding will continue along the Little Wabash River near Clay City for several days. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. 37
The national radar mosaic for the moment the first event began.
1 heat. Local standard time, as filed.
A 61-year old man was found unresponsive outdoors in Peoria on July 23rd. Temperatures at the time were in the lower 90s while heat index readings were around 107 degrees. The man was given emergency treatment for hyperthermia, but died in the hospital a short time later.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Heat, Peoria | 2025-07-23 | 61 | Male | Outside/Open Areas | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2025Every state in 2025This day in weather historyWarnings in Illinois, July 2025
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: 1277316.