The heat wave will peak on Friday when temperatures reach117 in Ocotillo Wells, 114 in Anza Borrego State Park, 113 in Valley Center, 111 in Santee and Ramona, 109 in Campo, 105 in Escondido, 99 in Julian and 87 on Coronado, according to the National Weather Service.

"Thursday will be warmer than (Wednesday), but (Friday is when) it's going to get reallyhot," said Jimmy Taeger, a weather service forecaster.

Forecasters aren't planning to issue a fire weather alert. Although temperatures will be high, the winds will be weak and the humidity will be in the acceptable range.