Columbia, SC (WLTX) - Wednesday marked the hottest day of the year in the Midlands with a high of 96 degrees and a heat index of 102. Temperatures are expected to go up throughout the week.

Be aware that the sun's rays are hottest between 10 am and 4 pm. So, it's best to stay indoors during those times.

If you are heading outside, make sure to apply sunscreen 15 minutes before you walk outdoors.

According to the National Weather Service, heat is one of the leading weather-related killers in the United States, resulting in hundreds of fatalities each year and even more heat-related illnesses.

Heat cramps, heat exhaustion and heat stroke are some of the illnesses that people outside can face.

Heat exhaustion can cause excessive sweating, clammy skin, dizziness, along with nausea. If you experience heat exhaustion, drink water and get to a cooler environment. A cold shower can also help.

Heat stroke can also cause nausea, as well as headaches and a body temperature of more than 103 degrees. If you are experiencing a heat stroke, you should call for emergency help.

For more heat safety tips, check out the National Weather Service site here.