The Weather Service has issued an excessive heat warning through 8 p.m., Wednesday, Aug. 25 for most of Southern California, including the city of Pomona. Temperatures are expected to rise around 105 degrees in the afternoon. The extreme heat and humidity may cause illnesses, such as heat stroke, heat exhaustion and heat cramps. People are encouraged to stay out of the sun, seek air-conditioned rooms and drink plenty of fluids.