Once your grass turns brown from lack of water, it goes dormant–no longer growing–leaving your lawn open to weeds. To keep your lawn healthy during the hot summer months be sure it receives 1″ to 1 ½” of water per week–whether from rainfall and/or watering. Most soils should be soaked to a depth of 6″ with each watering. A good soaking once or twice a week is better than a light sprinkling every day as this encourages deep root growth. The best time to water is early morning since evaporation rates are lower in cooler temperatures–meaning the water goes into your lawn and not in the air.
For more summer lawn care tips, read: How to Water Your Lawn Efficiently