The best way to water grass is to water infrequently and deeply two or three times each week during the morning hours when the sun and wind are less common. Home owners should water the lawn evenly and with sprinklers that equally distribute water to the entire lawn.
A rain gauge can be used to ensure at least 1/2 inch of water reaches the entire lawn when watering each time. A quick way to test the water level is to stick a 6-inch screwdriver into the lawn. If the screwdriver doesn't sink completely into the ground, the ground doesn't have enough water.
It is best to water more often in hot and humid temperatures. Light daily waterings in addition to deep waterings a few times a week helps to keep the grass hydrated when temperatures reach 90 to 100 degrees Fahrenheit daily. It is advisable to water during the hours of 6-10 a.m. to ensure the lawn has time to dry throughout the day. Watering the lawn in the evening invites fungus and mildew, whereas watering in the hot afternoon makes the water vulnerable to evaporation and wind. Lawns in the Southwest aren't affected by evaporation when watered in the evenings.