A growing dome of warm air will be expanding from the Great Plains into the Midwest. Excessive Heat Watches (dark brown on the map) or Heat Warnings (purple) are in effect across a large area from Illinois, to Minnesota and North Dakota, then south to Kansas.
People in different areas of the country acclimatize to heat events in different ways. What is common to heat related deaths or heat related injuries (heat exhaustion or heat stroke) is a lack of adjustment to the heat, along with dehydration and inadequate cooling. In places where summer air conditioning is not commonly used, those in poor health and the elderly can be most at risk.
Within the City of Chicago, where 739 deaths occurred over 5 days in 1995, many of these deaths occurred in homes where seniors lived without air conditioning or other adequate cooling, and where concern over crime made them reluctant to open windows. See the warning information posted by the NWS Chicago on this upcoming event.
Long range models indicate the heat will retreat from the Midwest to the southwestern US as we begin next week, with the heat likely affecting Nevada and California.