Updated at 11:41 a.m. ET
(CBS News) CHICAGO - Chicago remained under an excessive heat warning Thursday with temperatures again poised to exceed 100 degrees, and parts of the city are beginning to buckle under the strain, CBS Chicago station WBBM-TV reports.
With a high of 102 degrees Wednesday, Chicago tied a record dating from 1911 for the Fourth of July, and the forecast high for Thursday is even steamier, leading the city's public schools chief to cancel summer classes at 18 schools.
As of 5 a.m., it was already 80 degrees while the normal high for the day is only 84. The highs for the coming days -- 103 for Thursday and 104 for Friday -- are forecast to be a few degrees shy of the hottest temperatures ever recorded in the city.
(Watch at left a "CBS This Morning" report on the nationwide heat wave)
The city remains under an excessive heat warning until 10 p.m. Friday. The weather service advises minimizing time outside, wearing loose-fitting clothing, drinking plenty of water and scheduling frequent rest breaks.
On top of all that, an air quality alert is in effect through Thursday night for northern Illinois and northwest Indiana. Increased ozone levels will make stress on the body even worse, particularly for the very young or elderly and those with existing respiratory problems.
The ongoing heat wave is believed to be responsible for one death. Ioan Kendrick, 95, died Tuesday night at her home. While her autopsy has been deemed inconclusive, the Cook County Medical Examiner's office said her death may have been heat-related, according to published reports.
In addition, at least 232 people have been taken to area hospitals in Chicago so far because of the heat.
City officials are taking the heat wave very seriously, particularly due to the risk of heat exhaustion and heat stroke.
Some of the symptoms of heat exhaustion include heavy sweating, paleness, muscle cramps, a fast and weak pulse and fast and shallow breathing.
Untreated heat exhaustion can lead to heat stroke, which is defined by a body temperature of more than 105.1 degrees. Someone suffering from heat stroke may suffer from dry skin, a rapid pulse, dizziness, fatigue, seizure and hallucinations.
The heat has also taken a physical toll on the city, causing a huge section of pavement in one neighborhood to buckle Wednesday afternoon.
With temperatures topping 100 degrees, the pavement cracked and rose 2 to 3 feet into the air, prompting authorities to close the adjoining street, which officials were planning to close anyway to set up for a food festival.
No one was injured in the pavement buckling.