In this poem, Bronte uses rain to serve as a metaphor for gloom, despair, and even death. Early in the poem, she remarks that "morning rain" can lead to a "pleasant day." She adds that since rain makes the flowers bloom, we should not be gloomy or sad when the rain does fall.
remorse is feeling apologetic for your actions, on purpose or otherwise. an apology is taking accountability for your actions. If an apology starts with "I'm sorry but" it lacks accountability therefore is not a sincere apology