The mood of “The Three-Day Blow” is primarily a melancholic one, with a significant shift into a hopeful register near the end of the story. The dissatisfied mood is established early on in the story, as Nick and Bill meet up with each other at Nick’s father’s cabin in Northern Michigan and drink by the fire:
They sat in front of the fire and drank the Irish whisky and water.
“It’s got a swell, smoky taste,” Nick said, and looked at the fire through the glass.
“That’s the peat,” Bill said.
“You can’t get peat into liquor,” Nick said.
“That doesn’t make any difference,” Bill said.
“You ever seen any peat?” Nick asked.
“No,” said Bill.
“Neither have I,” Nick said.
This passage is extremely minimalist—all Hemingway offers readers is basic information about the scene and short dialogue between the two characters (always ending simply with “Nick said,” or “Bill said” rather than expounding on their tones or inner experiences). The lackluster nature of his prose adds to the story's overall depressive mood. The content of their conversation—whether or not “you can get peat into liquor”—is also mundane. The two men argue, but just barely, communicating that they don’t have the energy or passion to fully engage with each other.
The mood stays like this for much of the story, but it changes markedly near the conclusion, as Nick realizes that it’s possible he could get back together with his ex-girlfriend Marjorie someday. The following passage captures this shift in mood:
He felt happy now. There was not anything that was irrevocable. He might go into town Saturday night. Today was Thursday […] He felt happy. Nothing was finished. Nothing was ever lost. He would go into town on Saturday. He felt lighter, as he had felt before Bill started to talk about it. There was always a way out.
While Hemingway’s minimalist writing style stays the same, the mood clearly changes as the narrator shares Nick’s reflections: “He felt happy now,” “Nothing was ever lost,” “He felt lighter,” and “There was always a way out.” This is Hemingway’s way of communicating that even in the face of loss, no ending is truly final—just as the storm in the story will come and go, so, too, will Nick’s relationship with Marge (or so Nick hopes).