Yes they are summer tires. Most people will tell you there are no true high performance all season tires and that most "all season tires" are in reality 3 season tires. None of the OE BMW spec'd tires were all season for the E53 X5 and come winter you really should get a set of dedicated winter tires. Having said that you live in Southern California where it is effectively 1 season all year round with only rain to worry about. These tires are excellent in the rain and would be perfect for you. Just my 2 cents.