If you choose to irrigate, do it efficiently. Walk across your lawn. If your footprints remain in the grass very long, the lawn is dry. When a lawn is dry a long time, it will exhibit a bluish-gray cast. Watering brings back the color.
Dry grass responds by wilting and rolling or folding the leaves.
If the soil is very dry, it will be hard to insert a screwdriver into the lawn. If any of these techniques determine your lawn is dry, apply about an inch of water. If runoff is a problem, apply half and let it soak in. Then apply more. Early morning is the best time to water.