This poem uses highly symbolic language to create its images; it's not surprising that you are confused by the face value of the pictures created.
"During Wind and Rain" is the story of a family. In the first five lines of the first stanza, they are enjoying a candle-lit evening of making music, with one playing some instrument while three sing "their dearest songs." In contrast with this loving and peaceful scene, the final two lines of the stanza foretell how time will destroy the family, with illness separating the members like "sick leaves" falling from the tree "in throngs!"
The second stanza's first lines tell of the gardening tasks and pleasures shared by the parents and children. However, time goes by and "white storm-birds wing across", bringing death in the storm.
The children have grown up in the third stanza, as the family is now described as "men and maidens" as they share breakfast in a peaceful seaside setting. Time marches on; the "rotten rose" of one who becomes ill "is ript from" the family's midst.
In the last stanza, the family is moving "to a high new house" with all their furniture and prized possessions. Even in this new location, they cannot escape death - eventually they will die and the rain will fall on the gravestones bearing "their carved names."
Thank you, so very much. After reading this I gained a new understanding to not only this but his other works.