Weather alert conditions at the Atlanta Journal-Constitution Peachtree Road Race are now potentially dangerous as the temperature and humidity continue to rise.

The race, which uses an emergency alert system, started out Thursday morning at a yellow warning for runners to use caution and has now increased to a red warning alerting runners of potentially dangerous conditions.

At the start of the race, temperatures reached the upper 70s and are expected to reach the upper 90s by the afternoon. By the end of the race, temperatures should be in the upper 80s, according to the National Weather Service.

A heat advisory has been issued to start at around 1 p.m. today through 7 p.m., with a heat index expected to be between 105 and 109 degrees throughout metro Atlanta and South Georgia, Channel 2 Action News Meteorologist Brian Monahan said.