Firstly try to reseed your yard on the patches with the same grass seed. And start watering do not water daily, Water in weekly commonly grass need 1 to 2 inch water each week and fertilizer your lawn it will help the lawn grow up fast.

As per my knowledge you should have to plant new grass. First test your soil after that choose the grass seeds. Take advice from expert lawn care they will give you advice how to take on lawn. Or you can lawn turf directly its very easy and profitable.

Here is a link that might be useful: greenlawnturf

Because you are in zone 9, which is almost always in the very deep south, Ethanhh's seeding advice does not apply to you unless you have bermuda grass. We don't know what you have. If you are in the zone 9 in California, then you might have the so-called northern grasses. The rest of Ethan's message was difficult to interpret but fertilizing now with a chemical fertilizer is a really bad idea, again, unless you have bermuda. We need to know more about this.

Where do you live?
What kind of grass was there?
What kind of grass do you want?
Is shade an issue from trees, shrubs, fences, or buildings?
Are you willing to water once per week in the hottest heat of summer?
Do you have kids or pets which might wear a lawn out?

When I Said use chemical fertilizer why not you try Organic fertilizer. I am agree with you dchall its depend on Where he/she is live?, what type of grass.

I live in Southern California in an inland area so it gets very hot in the summer months, 100+. Right now it has been averaging 85-90 degrees. I honestly don't know why type of grass was here before. Just looks like the wide, flat blade grass I see everywhere. Both areas that we'd like to grow grass are basically in full sun. The front yard has a tree root issue. We are going to remove the tree soon but there are quite a few roots that have sprouted in the lawn area. We do have dogs but can keep them from the area while it is growing if needed. Thanks for all your advice!