Cool Season grass does best in spring and fall because it is cool at night and warm in the day. Hot, dry summer is the stress it doesn’t thrive with.
If you decide to water do it only in the early morning. Late evening watering causes fungus problems and gives you something else you then need to deal with.
How to keep it from dying?
Water it with 1/4 inch of water every 2-3 weeks. This won’t keep it green, in fact, it will probably start to turn brown. This is the look of your grass in the winter. It’s still alive though. It is just going dormant. The small amount of water will keep the crown of the grass alive and ready to grow in the fall.
How to keep it green in summer?
Water it two times a week with a 1/2 inch of water at each watering for a total of 1 inch of water a week. This provides water deep down and not just on the surface. This should keep it green through the summer until the better fall weather arrives.
How to measure the water?
You need to put a container out in the yard to catch the water. Check it after several minutes to measure how much water is in it. This way you will know how long to water to apply the amount of water needed.