The best grass seed for Southern California is a warm-season grass. For coastal locations where winter temperatures rarely dip below 40 degrees Fahrenheit, an ideal grass seed is Seashore Paspalum, which tolerates both salt and drought. For inland parts of Southern California with hotter summers, Bermuda grass is a good choice.
Growing grass in Southern California can be a tricky business, particularly due to water shortages and watering restrictions. You want to look for grass such as bermuda grass or zoysia grass. Both are good in full sun exposures.