We're having some oppressive heat right now in Texas. This type of heat can send a landscape into chaos. Especially new landscapes that are not established yet.
It is important, now, to supplement your watering with regard to the landscape plants/trees. That means you'll need to manually water with a hose.
I recommend you wait until the evenings to do this, when its cooler and the plants will get to spend much more time with the water (overnight).
How much water? Saturate the root ball areas, even those of ornamental trees.
For small trees of all types, employ the use of a Gator Bag which will slowly disperse water directly over the root ball.
During heat like we're having 105-114 degrees, we have to help our plants out a little more. Just standard sprinkler system watering is not enough.