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.

See sandy soil.  This will prevent water runoff.