Forecasters say the heat index is expected to top 105 degrees through Friday in some areas of the state.
The advisory has been extended until Thursday evening for the following counties: Bolivar, Claiborne, Hinds, Holmes, Humphreys, Issaquena, Leflore, Madison, Rankin, Sharkey, Sunflower, Warren, Washington and Yazoo.
"If you don't have any business outside, stay inside and be sure to check on your elderly relatives," said Bill Quinton, Bolivar County EMA Director.
According to the Mississippi Emergency Management Agency, approximately 175 Americans die from extreme heat in a year.
During peak temperatures the heat index is expected to range between 105 and 110 degrees today and Friday with lows in the mid to upper 70s, providing little relief from the heat.
Young children, senior citizens and those who are sick or overweight are more likely to become victims.
In an effort to remain safe citizens should stay indoors as much as possible, consider spending the warmest part of the day in buildings, drink plenty of water, limit the intake of alcoholic beverages, wear loose fitting clothing, never leave children or pets alone in closed vehicles, avoid strenuous work in the warmest part of the day, and protect face and head by wearing a wide-brimmed hat.
The following symptoms are usually associated with heat exhaustion: heavy sweating but skin may be cool or pale, weak pulse, body temperature may be normal but temperature will likely rise, fainting or dizziness, nausea, vomiting, exhaustion and headaches are possible.
If someone has symptoms of heat exhaustion, move the victim to a cool place, increase cool water intake, place cool wet towel on neck and underarms and seek medical attention if symptoms worsen.
Animals may also be severely affected during this heat advisory.
According to Dr. Andrea Marble, veterinarian at the Cleveland Animal Clinic, said, “Outside dogs should be kept in plenty of shade, their water should be changed twice a day and should include ice. Inside dogs should not be left in the car at any time and older dogs should be brought in during the warmest part of the day even if they are outside dogs.”