From biographical information we know that the morning Jack wakes up in San Francisco, the date is July 25, 1960. In the novel Jack writes that he will go mad "on the fullmoon night of 3 September." In retrospect, Jack either got his dates mixed up or altered the night of the full moon to suit his literary purposes: in 1960 the full moon fell on September 5th and not September 3rd.
What we do know is that the setting of Big Sur is extremely important to the text; we know this because of the not-so-subtle title of the novel. This makes us ask a question: what does Big Sur mean to Jack?
When the novel begins, Monsanto's cabin in the woods offers a chance to get away from the bustling city and the people in it. Jack first calls it "a refuge" (1.1) and then "an escape" (2.1), and the famous line "one fast move or I'm gone" (2.1) makes it clear that heading to the woods is as much about running away as it is about running towards. In Jack's "Character Analysis" we talk about his need for time alone, his self-imposed isolation, and the peace he finds while in solitude at Big Sur. Jack is seeking all of this – isolation, peace and solitude – in Monsanto's cabin.
As soon as Jack arrives at Raton Canyon, we see that Big Sur also has metaphorical significance – maybe not what Jack Duluoz has in mind, but certainly what Kerouac is driving at in his novel. (This represents more of that autobiography meets literary technique that we discuss in "Genre.") The ledge of the canyon appears to Jack "a thousand feet" high "with a sheer drop sometimes" (3.1). As we know from his repeated references, Jack himself is hovering on the edge of insanity, about to fall. (Keep in mind that Jack continually promises his reader that he will fall before the end of the novel). Big Sur is a scary, dangerous, and foreboding place; a complimentary setting for the story of a man six weeks away from a paranoiac, delirious breakdown.
The temporal setting of Big Sur is also important. Jack is tired of his image as "the King of the Beats" because the concept of the Beat Generation is no longer exciting. It's been popularized – the counter-culture movement has become mainstream. Jack writes of Ron Blake, "He comes on with that tiresome hipster approach that was natural 5 or 10 or even 25 years ago but now in 1960 is a pose." Jack is also dealing with the large-scale social changes he sees around him. The America of Big Sur is bigger, colder, less friendly than that of On the Road. "You can't get a ride anymore," he writes (10.3).
Speaking of transformations, think about the way the scenery of Big Sur changes along with Jack's mood during the course of the novel. Compare his deceptions during his first visit alone to his visions in Chapter Thirty-Seven. The contrast doesn't escape our author, either:
So I make supper with a happy song and go out in the foggy moonlight […] and marveled to watch the new swift gurgling clear water run with its pretty flashes of light […]. A whole mess of little joys like that amazing me when I came back in the horror of later to see how they'd all changed and become sinister, even my poor little wooden platform and mill race when my eyes and stomach nauseous and my soul screaming a thousand babbling words. (6.6-7)
Jack's emotions are manifest in the landscape. Notice that when Jack is insane and shivering in the midst of his delirium tremens, he describes the land around him as "an insane shivering canyon" (34.10). As strange as it may sound, Big Sur functions as an emotional barometer for Jack – the scenery lets us know what's up in the mind of our complicated, conflicted narrator.