The action in Ernest Hemingway's short story, "A Day's Wait," takes place over the course of one day. In the opening of the story, Schatz (the son) has been running a fever. His father, who remains unnamed, calls for a doctor. The doctor diagnoses Schatz with the flu and tells him that a temperature of 102 degrees should not be any concern, until it reaches 104 degrees.
Schatz's father maintains a bedside vigil until Schatz's preoccupation with his illness overcomes him. Schatz's father decides to go out to take the dog for a walk and hunt, while Schatz sleeps. Upon returning, Schatz's father takes his temperature (which has not changed). Schatz asks his father about his temperature and his father lies telling him it is only around 100 degrees.
After a conversation about the differences between the measurements of Fahrenheit and Celsius, Schatz's worry seems to change.
The next day it was very slack and he cried very
easily at little things that were of no importance.
Therefore, the title of the story is justifiable given the way Schatz's feelings seem to change after a day has gone by.