I'd like to understand why, in the last chapter of The Great Gatsby, the narrator says that Gatsby's father wears an overcoat "against the warm September day"? It would be logical to say "against the cold September day."
"It was Gatsby's father, a solemn old man, very helpless and dismayed, bundled up in a long cheap ulster against the warm September day."
This passage is ironic in nature as there is something at once both tragic and comedic about poor Mr. Gatsby. For, like his son he has believed in
a promise that the rock of the world was founded securely on a fairy's wing.
Carrying pictures of Jay Gatsby, Mr. Gatz reveres the material success of his son, even after his death. He shows Nick a book Gatsby kept when he was a mere boy, a book containing Jay's fastitdious entities:
He was reluctant to close the book, reading each item alound and then looking eagerly at me. I think he expected me to copy down the list for my own use.
However, it is always tragic whenever a parent loses a child, for such a death is out of the natural order. So, when Henry Gatz arrives from Minnesota, and he is "bundled up in a long cheap ulster," it is for the same reason that his "trembling hand" holds precariously the glass of milk: Mr. Gatz is traumatized by the horrendous news, cold with the chill of loss. The cold hand of Jay Gatsby's death passes over a man whose pride has been measured by his son's accomplishments.
The description of Gatsby's father, the coat he wore, and the warmth of the day is truly meaningful. It is at a point in the narrative where no one will come out to support or be near Gatsby. Having been killed, everyone disavows any knowledge of Gatsby. Meyer Wolfsheim expresses that he "cannot get tied up with this right now," Daisy is long gone with no forwarding address, and for a man who was constantly surrounded by people at parties, Gatsby, at his moment of reckoning in terms of death, is very much alone. The only person who comes to represent Gatsby, only after reading about it in the paper, is Gatsby's father.
It is evident that Gatsby's father is not as sophisticated in arriving to the "big city." He represents the humble origins from which Gatsby came. Nick's description of Gatsby fits the representation of someone from a rural setting arriving into the cosmopolitan urban one:
It was Gatsby’s father, a solemn old man, very helpless and dismayed, bundled up in a long cheap ulster against the warm September day. His eyes leaked continuously with excitement, and when I took the bag and umbrella from his hands he began to pull so incessantly at his sparse gray beard that I had difficulty in getting off his coat. He was on the point of collapse, so I took him into the music room and made him sit down while I sent for something to eat. But he wouldn’t eat, and the glass of milk spilled from his trembling hand.
The presence of a coat that was used "against the warm September day" makes sense. Gatsby's father is not really sophisticated enough to differentiate between when an ulster should be used and when it should not be. Gatsby's father probably owns only one coat and this coat is what he wore, recognizing both the funeral he will be attending and the "formality" of traveling into the city. The use of the ulster against a "warm September day" helps to show how out of place the old man is. He did not dress for the weather because it was not in his mind to do so. He dressed for the funeral of his son, one that pretty much disavowed his past. Had the day been cold, then Gatsby's father would not have been out of place in dressing the way he did. Given the warm day, and the presence of this loose, big coat, it was not really fitting, which represents how Gatsby viewed his past and how the old man recognizes the gulf between the young boy he once raised and the corpse of a man in front of him now.