We have some pretty drastic temp changes here. Summers are upper 90's, but it can be 60 at night. Winters get down in the twenties sometimes and we usually get at least one good snow each year although this past winter we got a few and one that lasted a few days. When the grass started dying off it was in the upper 90's and we were in a drought condition, but I was running the irrigation system twice a day. I did this until the grass was nice and thick and then I cut back to once a day and then 3 times a week and then twice a week (which is where I have run it since). That is what gets me - the grass grew in nice and thick and I was so happy. I actually had neighbors that I never met before stop in front of the house asking me for my secret...and then it died! One of the kicker's was I don't have a well so my irrigation system runs off my meter and my water bill was freaking astronomical. ALL FOR NOTHING!
A little more information - My oaks have quite a few roots that run at the surface, the turf under the soil I brought in is a hard packed clay - which somehow since the grass died the good soil has washed away and now my top layer is clay again. I am not sure where it has gone since my lawn is fairly flat with just a slight slope to one side - very slight slope. I also notice under one of the oaks there is a lot of moss (or what I believe to be moss) since the grass has died. I called in a Turf Management Company and they even couldn't guarantee grass to grow unless I sodded the entire yard for thousands of dollars and signed up for their monthly service plan = more $$$. I declined that plan. I am tempted to let mother nature do her thing and just put a huge island of landscaping in the front yard and forget the whole grass thing.