Let's talk about other symbols mentioned in the book :

•  Dr. Eckleburg eyes 

" The eyes of Doctor T.J. Eckleburg are blue and gigantic - their retinas are one yard high. They look out of no face, but, instead, from a pair of enormous yellow spectacles which pass over a nonexistent nose. Evidently some wild wag of an oculist set them there to fatten his practice in the borough of Queens, and then sank down himself into eternal blindness, or forgot them and moved away . But his eyes, dimmed a little by many paintless days, under sun and rain, brood on over the solemn dumping ground"..

The billboard with the eyes symbolize the loss of spiritual values in America. The billboard was erected to promote the business of an optometrist in Queensborough – the eyes symbolize the growing commercialism of America – life in America is all about making money. 

Wilson compares T.J.’s eyes with the eyes of God. He recounts to Michaelis what he says to Myrtle after discovering his affair, “‘and I said “God knows what you’ve been doing, everything you’ve been doing. You may fool me, but you can’t fool God!”” However, Michaelis tries to point out to him that “It’s just a billboard. These eyes saw Tom hurrying to  New-York city on his adulterous affair, Gatsby driving Nick to meet Wolfshiem, the man who fixed the World Series,  Daisy driving to Gatsby and the road accident with Myrtle.

Besides, the forgotten by everybody, the billboard symbolizes the hollowness of the American Dream. There is this idea that a person who comes from humble origins could achieve the Dream if they are willing to work hard and take advantage of opportunities, but this Doctor Eckleburg failed to prosper as many thouthands of people like him and thus he left . 

• Valley of the Ashes

 " This is a valley of ashes - a fantastic farm where  ashes grow like wheat into ridges and hills and grotessque gardens; where ashes take the forms of houses and chimneys and rising smoke and, finally, with a transcendent effort , of ash-grey men who move dimly and already crumbling through the powdery air. Occasionaly a line of grey cars crawls along an invisible track, gives out a ghastly creak, and comes to rest, and immediately the ash-grey men swarm up with leaden spades and stir up an impenetrable cloud, which screens their obscure operations from your sight..."

Valley of Ashes is an area where ordinaru working people live.  It is a place placed near the rail road and highway connecting New-York with West and East Eggs. 
It symbolizes a hard life full of despar and hopelessness. People living there like the Wilson's are eager to have a better lafi ( as well as early mentioned ghostly Dc. Eckleburg) but there is no opportunity for them to escape.  It's again a point against the realness of the American Dream : people do the best to improve their social position and living conditions but in vain - the following generations will remain doing the same. 
It also represents the plight of the poor people in America in 1920th. People like Wilson  live among the dirty ashes and lose their vitality and mind as a result.

• Weather 

The main purpose of introdustion the mentioning of wenther changes is to create an appropriate atmospere generally and to show the character's worries and emotions.

In chapter five, the element of weather is first introduced to the novel. Nick, because of Gatsby’s wishes, holds a tea and invites Daisy. On the day of the tea, a rainstorm begins and continues throughout the day. The rain is just that annoying, constant drizzle, with no thunder or lightning. This rain represents Gatsby’s nervousness of reuniting with Daisy. After many years of being away from his only love, who is now married, Gatsby’s is anxious of her arrival. 

When Daisy finally arrives at the tea, there is much tension between the two of them. They felt very awkward meeting each other for the first time in many years. Gatsby tries to impress her, while she doesn’t know what to say. Outside, the rain continues to pour down. The drizzle in this case therefore represents the tensions between Daisy and Gatsby. The weather emphasizes the problems and changes in both of their lives. It is used to set the mood of this part of the story. 

 Nick leaves the tea for a few hours, so the narration jumps in time. When he returns, he finds Gatsby and Daisy enjoying each other’s company. They are talking about their pasts as if there were never any problems. At this point in the tea the rain had stopped and the sun had come out. This weather shift represents the mood shift in the novel. When Gatsby and Daisy’s relationship cleared up so did the weather.

 At the beginning of this chapter, Gatsby’s previous life is revealed. We find out that Jay Gatsby was previously James Gatz and that he inherited his money from a man named Dan Cody. Gatsby first met Cody when he rowed out to his yacht to warn him of a coming storm. This storm represents a great change coming in Gatsby’s life; he becomes a good friend of Cody’s. As a result of this, Gatsby inherits his new name, his new personality, and Cody’s money; significantly changing his life.

Chapter seven takes place on the hottest day of the summer. This weather pattern sets up two connections between the climate and the plot of the novel. First, the connection of the heat to the mood of the story is made. The hottest day of the year also happens to be the day Gatsby confronts Tom about his love with Daisy. The heat intensifies the tension between the two. The heat and the fight soon become unbearable and both Gatsby and Tom snap.

            The other connection created in this chapter is the link between the summer and Gatsby’s hope for attaining Daisy as his love. Daisy’s and Gatsby’s relationship happens to peak on the hottest day of the summer. Their love is at the greatest and in turn Gatsby’s hope is the highest it has been all summer. Similarly, the heat is also the highest it has been all summer, creating the connection. 

 Chapter eight concludes the use of weather in the novel. The connection made in this chapter was first introduced in chapter seven and consists of the relationship between Gatsby’s dreams and the summer. The weather from the previous chapter to this one dramatically shifts from summer to autumn. Gatsby’s hope of love with Daisy also shifts downhill in this chapter; it is basically over between the two of them. In turn, the autumn season represents the death of Gatsby’s dreams.

          Even though his dreams are dead, Gatsby does not want to let go of Daisy; he still loves her. This is represented by Gatsby’s swimming pool. A pool represents summer life, a life that was over on the autumn day described. But such as Gatsby could not let go of Daisy, he couldn’t let go of summer and decided to swim in his pool. Soon after getting in the pool, he is killed. On his deathbed, Gatsby longed for Daisy as he longed for summer to return.