The National Weather Service said the heat advisories were mainly in southwestern and central Ohio. Excessive heat warnings continued for Dayton and Cincinnati.
An excessive heat warning is issued when heat and humidity combine to make it feel like 105 degrees (41 Celsius) or greater.
Authorities urged Ohioans to continue taking precautions such as drinking plenty of water and limiting time in the sun.
Meteorologist Ashley Novak, in the Weather Service's Wilmington office, said clouds and precipitation moving into northern Ohio by afternoon and southern Ohio by night should lower Monday's temperatures to the 70s.
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