The mood of "A Sound of Thunder" is adventurous and anticipatory, since the reader follows Eckels on his daring journey to hunt a Tyrannosaurus 60 million years ago. The story's abundant use of foreshadowing amplifies the feeling of anticipation, which keeps the reader on the edge of their seat, waiting for the hunt to take a turn. From the first page of the story, the reader predicts the danger of the hunt and empathizes with Eckels's nerves:
A warm phlegm gathered in Eckels' throat; he swallowed and pushed it down. [...] "Does this safari guarantee I come back alive?"
The story immediately clues the reader into its tragic ending. With each new piece of information about time travel, the anticipation builds, hurtling towards the climactic death of the Tyrannosaurus. Ironically, Eckels comes back from the safari alive, but does not survive the wrath of Mr. Travis once they return.
Due to the futuristic backdrop of the story, the mood is also curious. The story uses fictional technology such as the Time Machine to pique the reader's interest and create speculation about the possibilities of the future. Political discussions also raise questions about what the reader considers a sensible government to be in terms of personal freedom and access to technology.