The symbolism present in Bradbury's story points to mankind's proclivities for waste, pollution, and destruction, contrasted with the purity and regenerating forces of the natural world.
Even after the family has been obliterated in the nuclear blast, the house continues to consume and waste: it prepares meals that no one eats, cleans the dishes, and flushes the uneaten food "away to the distant sea." The house wastes water on the lawn, as the "sprinklers whirled up in golden founts." Beyond the house, "the ruined city gave off a radioactive glow which could be seen for miles."
Nature, however, goes about its everyday business: the sun continues to rise and set, the sun shines, and the soft rains come. Fire, one of Nature's most elemental forces, ultimately consumes the house that is symbolic of man's ostensible superiority, but at the story's end, "dawn showed faintly in the east."
Bradbury symbolically suggests that Nature has the capacity to outlive humanity's ruinous ways.