Heat, McHenry
- When
- July 21, 11:00 AM CST to July 25, 8:00 PM CST
- Where
- McHenry forecast zone
- Reported by
- GOVT OFFICIAL
- Coordinates
- 42.324, -88.452 (the zone’s center; the record gives no point)
Heat in Illinois, July 21 to 25, 1999
A moderate heat wave began in the Chicago metropolitan area on July 21 and continued through July 25. A weak lake breeze moderated temperatures along the immediate lakefront on the 21st and 22nd, but the intense heat spread inland through the entire metro area on the 23rd through the 25th.
Where it happened
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
The toll
- Deaths
- 13
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 7
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.
What happened
The episode as NWS LOT wrote it up.
A moderate heat wave began in the Chicago metropolitan area on July 21 and continued through July 25. A weak lake breeze moderated temperatures along the immediate lakefront on the 21st and 22nd, but the intense heat spread inland through the entire metro area on the 23rd through the 25th. Daily high temperatures were mostly in the lower to middle 90s at both O'Hare and Midway airports through the episode, with a peak of 98 at Midway on the 25th. Maximum heat indices were 103 to 111. In 4 of the fatalities, heat stress or heat stroke was the primary cause of death, it was the secondary cause in the other fatalities.
The radar
The national radar mosaic for the moment the first event began.
Event by event
7 heat. Local standard time, as filed.
Heat, Will
- When
- July 21, 11:00 AM CST to July 25, 8:00 PM CST
- Where
- Will forecast zone
- Reported by
- GOVT OFFICIAL
Heat, Cook
- When
- July 21, 11:00 AM CST to July 25, 8:00 PM CST
- Where
- Cook forecast zone
- Deaths
- 12 direct, 0 indirect
- Reported by
- GOVT OFFICIAL
Heat, Du Page
- When
- July 21, 11:00 AM CST to July 25, 8:00 PM CST
- Where
- Du Page forecast zone
- Reported by
- GOVT OFFICIAL
- Coordinates
- 41.852, -88.086 (the zone’s center; the record gives no point)
Heat, Kane
- When
- July 21, 11:00 AM CST to July 25, 8:00 PM CST
- Where
- Kane forecast zone
- Deaths
- 1 direct, 0 indirect
- Reported by
- GOVT OFFICIAL
- Coordinates
- 41.939, -88.429 (the zone’s center; the record gives no point)
Heat, Kendall
- When
- July 21, 11:00 AM CST to July 25, 8:00 PM CST
- Where
- Kendall forecast zone
- Reported by
- GOVT OFFICIAL
- Coordinates
- 41.591, -88.429 (the zone’s center; the record gives no point)
Heat, Lake
- When
- July 21, 11:00 AM CST to July 25, 8:00 PM CST
- Where
- Lake forecast zone
- Reported by
- GOVT OFFICIAL
- Coordinates
- 42.349, -87.862 (the zone’s center; the record gives no point)
The people who died
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, Cook | 1999-07-22 | 56 | Male | Vehicle/Towed Trailer | Direct |
| Heat, Cook | 1999-07-22 | 73 | Female | Outside/Open Areas | Direct |
| Heat, Cook | 1999-07-23 | 79 | Female | Permanent Home | Direct |
| Heat, Cook | 1999-07-24 | 56 | Male | Vehicle/Towed Trailer | Direct |
| Heat, Cook | 1999-07-25 | 47 | Male | Permanent Home | Direct |
| Heat, Cook | 1999-07-25 | 60 | Male | Outside/Open Areas | Direct |
| Heat, Cook | 1999-07-25 | 64 | Male | Outside/Open Areas | Direct |
| Heat, Cook | 1999-07-25 | 67 | Female | Permanent Home | Direct |
| Heat, Cook | 1999-07-26 | 91 | Female | Permanent Home | Direct |
| Heat, Cook | 1999-07-27 | 91 | Female | Permanent Home | Direct |
| Heat, Cook | 1999-07-28 | 77 | Male | Permanent Home | Direct |
| Heat, Cook | 1999-07-26 | 55 | Female | Permanent Home | Direct |
| Heat, Kane | 1999-07-22 | 39 | Male | Business | Direct |
What these are
- Heat
- Heat below excessive heat criteria that still caused deaths, injuries or significant impacts.
After NWS Directive 10-1605, the rules offices file Storm Data by.
The same day elsewhere
- Lightning Strike in Colorado, July 21, 1999
- Tornadoes and Hail in Montana, July 21, 1999
- Flash Flood in New Mexico, July 21, 1999
- Lightning Strike in Florida, July 21, 1999
- Flash Flood in Nebraska, July 21, 1999
- Flash Flood and Hail in Virginia, July 21, 1999
- Damaging Winds in Illinois, July 21, 1999
- Damaging Winds in Michigan, July 21, 1999
- Damaging Wind in North Dakota, July 21, 1999
- Hail and Damaging Winds in Ohio, July 21, 1999
- Damaging Winds in Ohio, July 21, 1999
- Hail and Damaging Winds in Georgia, July 21, 1999
More
Every storm in Illinois in 1999Every state in 1999This day in weather historyWarnings in Illinois, July 1999
Sources
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: 5710057, 5710058, 5716083, 5716084, 5716085, 5716086, 5716087.