Ground-level ozone concentrations will rise with the temperature today, leading the S.C. Department of Health and Environmental Control to declare an air quality action day.
The code orange air quality alert covers the Midlands and most of the Upstate. People with respiratory disease, including asthma, should limit prolonged outdoor exertion.
The National Weather Service forecast calls for a high temperature of 101, well below the 105 record for the day but still plenty hot to cause problems.
On Wednesday, Columbia Metropolitan Airport registered a high of 101, tying the warmest temperature of the year. Most of the other National Weather Service sites in the state had highs in the upper 90s.
The heat wave is expected to slack off slightly this weekend, when a front brings the possibility of afternoon showers and highs in the lowers 90s Saturday and Sunday, according to the weather service.