Ephelides is essentially a type of freckling on the skin. The appearance of the colored spots, or freckles, is due to collection of pigment in skin cells (keratinocytes). Ephilides occurs most in the summer months because of exposure to the sun, and the spots usally fade by the winter as the new skin cells form and exposure to the sun is more limited. Protection from the sun is the only real treatment for it. A sunscreen with a high SPF (Sun Protection Factor) is best.

Source: http://www.emedicine.com/derm/topic121.htm