Could potentially be overwatering but i'll let the experts chime in. 1" per week is about what you wan't under those conditions.

You are definitely overwatering. However lets look at a bigger issue first. With temps in the low 100s, you have the wrong grass type. You should have either bermuda or St Augustine. Fescue lawns might not be the entire reason California has a drought, but it definitely contributes to the problem. Fescue can be grown successfully in the morning fog zone or above 3,000 feet in California. If you aren't there, then you should be growing a warm season grass like bermuda or St Augustine. You can convert to either of those using sod any time of year. Or you can seed bermuda in late June or July. These warm season grasses love the summer heat.

Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall.

Why do you have so many utility holes in your yard?