A large system of low pressure produced widespread thunderstorms which impacted northern Illinois on the 18th. The storms produced damaging winds and torrential rainfall leading to instances of minor flooding during the early afternoon with additional heavy rain continuing into the evening.
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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 LOT wrote it up.
A large system of low pressure produced widespread thunderstorms which impacted northern Illinois on the 18th. The storms produced damaging winds and torrential rainfall leading to instances of minor flooding during the early afternoon with additional heavy rain continuing into the evening.
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 Chicago, IL wrote its last area forecast discussion before the first event at Jun 18, 5:30 AM CST, 4 hours 30 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 630 AM CDT Wed Jun 18 2025 .KEY MESSAGES... - Thunderstorms redevelop from the west by midday, and are expected to persist across much of the area through this afternoon with a severe weather risk continuing. - Stretch of hot and humid conditions with peak afternoon heat indices possibly over 100 degrees this weekend into early next week. && .DISCUSSION... Issued at 403 AM CDT Wed Jun 18 2025 Through Thursday: Main forecast concerns in the near term are thunderstorm trends and severe weather potential across the area today, along with the potential for locally heavy rainfall amounts. SPC's Day 1 outlook has expanded the enhanced risk a little farther north into the southern parts of the Chicago metro area, generally south of where last evenings convection has tracked. Early morning water vapor imagery depicts a synoptic mid-level short wave trough upstream (roughly through the Missouri River valley), likely convectively-augmented by the MCS/MCV over far southeastern KS. A couple of smaller MCVs were evident in regional radar data as well, one over central NE, another over northeast IA, and one lifting northeast out of southeast WI which brought our evening storms. Expectation is that there will be a relative lull in shower and isolated thunderstorm activity here early this morning in the wake of this departing MCV, before thunderstorm chances increase again mid-late morning ahead of the approaching short wave and embedded KS MCV. While still depicting more spread than desired, guidance is in general agreement in developing an associated surface low pressure wave across the forecast area this afternoon, backing low-level flow. Meanwhile, mid-level winds are forecast to increase to 40-50 kts along the southern periphery of the MCV, across central IL/IN and the southeast portion of the WFO LOT cwa. Warm and humid low- level air mass (low-mid 80s temps upper 60s dew points) is forecast to support 1500-2000 J/kg of MLCAPE, with 50 kt deep layer bulk shear expected to support organized convection in the form of clusters and line segments, and upscale growth into a more solid squall line appears possible across the southeastern parts of the forecast area this afternoon. A little bit of a warm layer in the 500-400 mb layer per forecast soundings weakens mid-level lapse rates somewhat aloft, with damaging wind gusts the primary expected severe weather threat. Backed low-level winds near/south of the low track will also support a tornado threat as well.Precipitable water values around 2" will also support the potential for torrential rainfall with storms during the midday and afternoon hours, with locally heavy rainfall amounts in excess of 2" possible. Storm coverage and severe threat should decrease late this afternoon as the low moves east of the area, though the upper trough axis will be slow to move across the region overnight into early Thursday morning. This will likely maintain scattered showers and isolated thunderstorms through the overnight hours and into early Thursday before strong subsidence develops by afternoon. SPS has maintained a marginal (level 1 of 5) risk for Day 2 across our far northern counties, though the potential appears to be higher north of the IL/WI border. Ratzer Thursday Night through Tuesday: Main focus through the extended period continues to be building heat and humidity this weekend into at least early next week. Broad upper level ridging will be building across the Rockies and high Plains Thursday as upper troughing shifts east across the Great Lakes. This will place the local area under a northwesterly flow aloft ahead of the building ridge to the west. This set up will support the passage of subtle shortwaves through the northwest flow which may result in some isolated shower/thunder chances, especially across far northern Illinois later Thursday or Friday. Better chances look to be to the north so most if not all areas may remain dry. A closed upper low upstream over the west coast is progged to further amplify the downstream ridge and push it eastward into the weekend. This will bring in much warmer air by Saturday with a breezy southwesterly low level flow setting up across the area. With such an amplified pattern, the ridge axis will extend well north of the area by Sunday, which combined with the fairly northerly position of the base of the western trough would keep the favored track for showers and thunderstorms north of the area through the weekend. Given that we're still a few days away from this pattern shift, we'll have to monitor how the amplitude of the upper features evolves over the next few days to see if the signal for convection to be favored to the north persists. The question going into early next week is how quickly the amplitude decreases and when a favored track for thunderstorms returns to the area as well as how quickly the heat abates. As far as temperatures, 850 mb temps are expected to warm into the 21-23C range for the weekend. Breezy south to southwest surface winds will support strong warming with highs expected to reach the mid 90s for most areas both Saturday and Sunday, and likely into Monday and perhaps Tuesday as well. Dewpoints are forecast to reach the lower 70s but this will be another element to monitor as drought currently persists across the area. Rain from today's thunderstorms may impact this, but Thursday and Friday will likely allow for drying out of the top layers of the ground. Given this, and the early stages of crop growth (as opposed to mature stages in July and August which allows for crops to add a notable amount of water vapor to the air) there is some concern that current dewpoint forecasts could be a bit too high. A drier airmass would allow for higher temperatures in the upper 90s. Ultimately, a hotter/drier scenario could net a similar heat index as a slightly less hot/more humid scenario with the resultant messaging of taking heat precautions being the same. At this point, the bigger concern is the duration of the heat as opposed to heat reaching an extreme or unusual magnitude. MDB/Ratzer && .AVIATION /12Z TAFS THROUGH 18Z THURSDAY/... Issued at 630 AM CDT Wed Jun 18 2025 Key Aviation Messages for the current TAF period: - Thunderstorms expected this afternoon - MVFR cigs/vis this afternoon remaining through the overnight, with a chance for IFR this evening While spotty showers this morning cannot be ruled out, there should be a lull in the rain activity for the next couple hours. Winds are slightly variable at present due to how light they are, but will slowly increase and prevail out of the southwest through much of the day. A system of showers and storms is expected to move over the region late this morning with increasing coverage of storms into the afternoon. As confidence has increased, the PROB30 was converted to a TEMPO for the current expected timing for the period of strongest storms as well as VCTS covering the early onset and lingering storm timing. MVFR cigs and vis are expected with these storms through the afternoon and into the night. There is still a chance for IFR conditions to be attainable, mainly in the evening/early overnight. However, conditions should generally improve to VFR conditions by day break. Models due have a weak signal for a wave of light showers before 12Z, but with the probability below 30 percent, it was left out of the TAF presently. Winds will become northwesterly this evening between 5 to 10 knots through Thursday morning. DK && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && Visit us at weather.gov/chicago
Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
446 AM CDT Wed Jun 18 2025
ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-191000-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
446 AM CDT Wed Jun 18 2025 /546 AM EDT Wed Jun 18 2025/
This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.
.DAY ONE...Today and Tonight.
Weather hazards expected...
Significant Thunderstorm Risk...with an associated:
Level 3 of 5 Damaging Wind Risk...up to 70 mph.
Level 2 of 5 Tornado Risk.
Level 2 of 5 Large Hail Risk...up to quarter size.
Elevated Flooding Risk.
DISCUSSION...
Thunderstorms are expected today, becoming more numerous late
this morning and this afternoon. Some of these storms may be
severe, especially along and southeast of I-55 across eastern
Illinois and northwest Indiana. Damaging winds, large hail and
tornadoes are possible, in addition to locally heavy rainfall.
.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.
Thursday and Friday...
Limited Thunderstorm Risk.
Saturday through Monday...
Limited Excessive Heat Risk.
Tuesday...
Limited Thunderstorm Risk.
DISCUSSION...
Hot and humid weather is expected to develop this weekend into
early next week. Peak afternoon heat indices at or above 100
degrees are expected.
Isolated strong storms are possible across southeast Wisconsin
Thursday afternoon and evening, and again Friday afternoon. A few
of these could clip far northeast Illinois near the Wisconsin
border, with a brief damaging wind and hail threat.
.SPOTTER INFORMATION STATEMENT...
Spotters will likely be needed this afternoon.
GENERAL STORM MOTION OF THE DAY:
Moving toward the east-northeast at 30 mph this morning, and
to the east at 35 to 40 mph this afternoon.
LMZ740>745-191000-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
446 AM CDT Wed Jun 18 2025
This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.
.DAY ONE...Today and Tonight.
Weather hazards expected...
Significant Thunderstorm Risk...with an associated:
Level 3 of 5 Thunderstorm Wind Gust Risk...up to 55.
Level 2 of 5 Hail Risk...up to quarter size.
Isolated thunderstorm Waterspout Risk
.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.
Thursday and Friday...
Limited Thunderstorm Risk...mainly north of Chicago.
Saturday...
Hazardous conditions for small craft are likely.
Tuesday...
Limited Thunderstorm Risk.
Ratzer
Visit us at www.weather.gov/chicagoThe Chicago radar (KLOT), 22 km away, was scanning. The volume nearest the first event began at 16:00 UTC.
10 heavy rain, 8 flood, 3 thunderstorm wind. Local standard time, as filed.
A personal weather station recorded 2.83 of storm total rain through 4 PM LST. 2.06 were recorded in less than one hour, and about 1 was recorded in the span of 10 minutes ending around 3:47 PM LST.
A personal weather station in Plainfield recorded 2.62 of storm total rain through 5 PM LST, 2.05 of which were recorded in one hour.
A private weather station recorded 3.91 of storm total rain through 6 PM. 1.12 were recorded in a 30-minute period.
Multiple reports were received of minor yard and agricultural flooding near Piper City and Cullom.
A personal weather station near Piper City recorded 1.7 in the first roughly 90 minutes since rain had begun, 1.45 of which fell in about 15 minutes.
A personal weather station in Stelle recorded 1.71 during the first roughly 75 minutes since rain had begun, about 1.6 of which fell within a 30 minute window.
A personal weather station near Clifton recorded a storm total rainfall of 2.77, 2.31 of which fell over the span of about 30 minutes.
A 50-foot tree fell and impacted a house along Bayles Lake. A living room window was shattered due to the impact.
A personal weather station recorded 2.09 of storm total rainfall, 1.73 of which fell over a 30 minute period.
A Cocorahs observer recorded 1.13 of rain in about 40 minutes in Bradley.
Two cattle structures collapsed on a farm near Shelton.
A cooperative observer reported minor flooding of rural roads near Chatsworth.
A private weather station in Rockford recorded 1.81 of rain in less than one hour and 2.45 of between 3 and 5 PM LST.
A personal weather station recorded 1.21 in just under an hour in Polo.
Alpine Rd was reported flooded near Broadway in Rockford.
Multiple reports of flooding were received from around the north side of Plainfield.
Multiple reports of street flooding were received from northern Romeoville and southern Bolingbrook.
Standing water was reported at the intersection of Burrmont Rd and Verble Pl in Rockford.
An NWS employee reported standing water in a few spots along Ogden Ave east of Finley Rd.
Three to four inches of standing water were reported in low lying areas of Orland Park's Alpine subdivision.
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, June 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: 1271680, 1271684, 1271686, 1269534, 1269557, 1269542, 1269545, 1269531, 1269559, 1269554, 1269536, 1269538, 1269623, 1271685, 1271681, 1271682, 1271683, 1271687, 1271688, 1271689, 1272801.