In Kate Chopin's short story. "The Story of an Hour," Mrs. Mallard has recently found out that her husband had died. Stricken with what readers, and her family, believe to be grief, Mrs. Mallard escapes to her room to "mourn."
While in her room, Mrs. Mallard comes to decide that the death of her husband is not a bad thing. Her life with him has been oppressive and hard. Now, with him gone, she is able to celebrate life. Her celebration first comes when she realizes the beauty of nature and the new life budding outside. Like the spring, Mrs. Mallard wants to forget her past and bloom.
The rain, therefore, symbolizes new beginnings and the washing away of the past. It is as if the rain is both cleansing her and nourishing her (given its physical nature (wet and cleansing) and its figurative nature ("delicious")). Mrs. Mallard could feel the change coming.