The grass will turn grey, and leaves will roll up. On centipede lawns, this should be done every week or so. A little exploratory surgery reveals another problem. A shovel will not penetrate the dry ground very deeply. The soil under this lawn is compacted.
Roots are the veins and arteries of the plant.
If the soil is hard, dry or too wet, they develop poorly and cannot maintain the top. Consequently, those plants do poorly or die. The best thing would be open heart surgery. Take up the grass, till and put it back down. This is often too much work for most people.