How do I keep my grass from dying in the summer heat?

I have read that lawns should not be shallow watered as they only develop shallow roots and dry up. Better to deep water (longer time) one time a week to develop deep roots and resistance. Worth a try.

Water deeply and only in the morning,watering at night will create a fungus

Hmmm this is an article about caring for your lawn in extreme heat. You may not be watering deeply enough, meaning for a long enough time. Grass needs to get it's water below the bottom of the roots in order grow strong. If you don't water deeply enough, the roots will turn up to get the water and that will cause them to turn brown or die.

Read this article to see if it helps:

https://yardcare.toro.com/maintain/how-to-maintain-the-grass-in-extreme-heat/

Maybe you are watering too much. What area of the country are you in? Do you get rain in the summer. I'm in Florida and we get quite a bit of rain so we only run the sprinklers 3 times a week In the summer and the grass is fine even with our high temps.

If you are not any water restriction, it needs a good soak at least 2 - 3 times per week. 30 minutes (approximately) so the water has time to soak in, penetrate the roots. Here is a link that explains it really well.

http://www.greengrassok.com/greengrass-services/how-to-water-your-lawn

Water in the middle of the night or when sun will not be out until the water soaks in. Otherwise, the sun is drawn to the wet grass and burns it.

I live in extreme summer heat in North Central Texas (dry and over 100' many days) and I hardly ever water my yard. First, the grass needs to be the type that can stand heat and sun. We have Bermuda grass. The key is to keep it healthy. I have been using Jerry Baker's tonic formulas from his book "The Impatient Gardner" for years and only water the grass maybe once a week June thru September. The book is paperback and has tons of other great and mostly non-toxic hints for anyone with a yard. Best of luck!

Best time to water is After (or At) dawn, before midday heat. Overnight watering offers environment for lawn fungus!