pre water prior to heat wave

Though practicing deep high infrequency, wonder if its wise to water a bit prior to predicted "heat waves."
In my current sitch I have deeply watered and fertilized w/ ringer last week. We have unusual heat predicted for this week.
A little morning moistening?
my dwarf fescue seems to prefer the shade, but thats a done deal.

Wait until the grass needs water. 

A week of heat will help to dry out the surface - killing weeds and the like, and train the grass roots to go deeper.  When the grass needs more water, then water deeply.