The big rain of the Great Gatsby occurs in chapter 5. By the end of the Chapter, the sun has come out and chapter 6 begins with Nick narrating Gatsby's past and his catapult from poverty to wealth.
The rain in Chapter 5 is a symbol of the confusing and never quite realized relationship between Gatsby and Daisy. After an unseen struggle or discussion (we really don't know what because the narrator went outside) Daisy and Gatsby re-emerge as a couple when the sun comes out and they head over to the illuminated home of Gatsby.
This affects the plot as a moment in the rising action of the story. The rising action is intended to provide complications that build suspense and make us wonder what is going to happen next. The rain makes it difficult for a while for her to truly see Gatsby's wealth. Our not knowing what happened builds over there at Nick's house builds suspense. We aren't sure as readers how their relationship is rekindling or redeveloping.
Chapter 6 then, gives background to their previous knowledge of each other and a deeper look into Gatsby. The holding off of the rain during six and filling us in on the background gives a little relief to the reader.
The weather in The Great Gatsby is worthy of note as it echoes the emotional tone of the story. Gatsby and Daisy’s reunion begins in pouring rain suggesting an awkward and melancholy event; their love reawakens just as the sun begins to come out. This happens in Chapter 5.
At the end of Chapter 6 Nick and Gatsby talk to each other. Gatsby tells Nick that he is worried that Daisy did not like the party; moreover he talks a lot about the past, especially about the moment when he kissed her for the first time and fell in love. Nick tells the reader of an evening Gatsby and Daisy spent together in their youth. The moment was so perfect and beautiful to Gatsby that he has spent all of his time trying to recreate that moment. It is this recreation that he believes will make him happy. In a novel which contains such images of heat, ashes and other images of inferno, rain also suggests an opportunity for regrowth and renewal. Rain washes clean, this echoes the imagery of grubbiness and corruption.
At Gatsby’s funeral, the rain represents more than just sadness. What is most significant about this rain is a quote one of the attendants or the minister at the funeral says: “Blessed are the dead that the rain falls on” (183). This is clearly an allusion to either the English poet Edward Thomas or the famous 17th Century English proverb, “Blessed are the dead that the rain rains on”