CHICAGO, Aug. 23 (Xinhua) -- The temperature at O'Hare International Airport in Chicago, the third most populous city in the United States, reached 98 degrees Fahrenheit (36.67 degrees Celsius) Wednesday afternoon, breaking the city's previous daily high temperature record for Aug. 23 of 97 degrees Fahrenheit (36.11 degrees Celsius), according to the U.S. National Weather Service.
The previous record for Aug. 23 was set in 1947, Chicago Sun Times reported on Wednesday.
By early Wednesday afternoon, the heat index was at 116. The highest heat index on record at the city of Chicago's official climate site is 118, set on July 13, 1995, according to the report.
The National Weather Service has issued an excessive heat warning for northern Illinois effective until 9 p.m. Wednesday, and an excessive heat watch from Wednesday evening through Thursday evening.
To help residents and visitors find relief from the heat, Chicago's Office of Emergency Management and Communications sent out a statement on Tuesday, listing the city's 27 cooling centers as well as Chicago Public Library locations and Chicago Park District field houses.
The Salvation Army is also opening its community centers as cooling centers across Chicago, the statement said.
In an email to district families on Tuesday, Chicago Public Schools (CPS) CEO Pedro Martinez said the school district has postponed all outdoor athletic events and will either be canceling practices or moving them indoors during the heat wave.
Martinez suggested students bring full water bottles to school, and they can refill water bottles throughout the day. Other measures planned for Wednesday and Thursday include opening windows and doors to keep air circulating; closing shades, turning off overhead lights and limiting recess.
All CPS classrooms are equipped with air conditioning, and the CPS facilities team will be working with schools to fix any air conditioning systems that may encounter issues this week, Martinez wrote.
Weather officials have warned that the extreme heat combined with humidity increases the chance for heat-related illness, recommending drinking plenty of fluids and staying in air-conditioned rooms.