Be sure to water as early in the morning as possible to avoid evaporation. This also helps reduce fungal diseases by giving the grass time to dry out during the day. Poor watering practices are the main reason for dead and dying areas in lawns and a common source of urban runoff.
Lawn care in the cool season is different from in the summer. With cooler weather, shorter days and the possibility of rain, lawns need less water. Adjust the sprinklers monthly based on the weather. Even better, get a smart controller that, once programmed, automatically adjusts for the conditions.
October is a good time to dethatch and aerate. Thatch is the layer of living and dead grass material (blades, rhizomes, stolons) that can build up on the surface of the lawn. A thin layer protects the soil surface and shallow roots from drying out from the sun, but a thick layer prevents water from getting through. You can remove dead grass material on the soil surface with a special thatch rake to allows water to reach the roots more easily.
More Information: UC Guide to Healthy Lawns