Every lawn should be watered as early as possible, 4-7 am is ideal. If you have to water twice in one day, water a 2nd time 12 hours later. Watering in the afternoon, when the sun is at its strongest, could have the reverse effects. Wet grass could act as a prism for the beaming sunlight and make it easier for the sun to burn up your lawn.
You have to use heavy watering to get where the roots extend. When temperatures are above 90 degrees, you may need to water once a day, 30-40 minutes each zone. Below 90 degrees, water once every other day, for the same amount of time.