The increasing coldness of the city is referenced several times to foreshadow the Swallow’s eventual death and emphasize the virtue of his sacrifice. When the Prince first asks the Swallow to stay a night, the Swallow objects, saying he is awaited in Egypt. However, when the Prince pleads with him to stay to help the boy in the city, the Swallow relents:
“It is very cold here,” he said; “but I will stay with you for one night, and be your messenger.”
The Swallow’s objection to the cold hints at the city’s inhospitable conditions, since the fact that the Swallow’s friends already migrated to Egypt six weeks earlier ultimately foreshadows his eventual death. The Swallow’s concession that he will stay one night despite the cold highlights his sacrifice, with his compassion for the Prince’s desire to help the boy compelling him to put himself at risk. The danger that the Swallow puts himself in by delaying his trip is reiterated again when the Prince asks him to stay another night:
“It is winter,” answered the Swallow, “and the chill snow will soon be here. In Egypt the sun is warm on the green palm-trees"
In this passage, the coldness of the city is further emphasized by its contrast with the warm sun and luscious greenery of Egypt, where the Swallow’s companions are. The Swallow’s mention that the “chill snow will soon be here” highlights the passing of time in the story, adding a sense of urgency with the winter only getting harsher and thus foreshadowing that it will soon be too late for the Swallow to leave. Indeed, the escalation soon becomes clear:
Then the snow came, and after the snow came the frost. […] long icicles like crystal daggers hung down from the eaves of the houses[...]
The simile “like crystal daggers” highlights the dangerous and indeed fatal power that the winter possesses. The association between death and the cold that this image creates is intentionally stark at this point, with the Swallow’s death fast approaching. This use of foreshadowing through the escalating descriptions of the harsh coldness of the city works as a narrative device to build tension toward the climax of the Swallow’s death, but also as a way to emphasize the nobleness of the Swallow’s sacrifice.