the biggest ironic facet of gatsby and daisy’s reunion at nick’s cottage is how awkward things are. gatsby has planned his entire adult life around the moment he will finally see daisy again and win her over.

however, the meeting is not what the reader—or gatsby—expects at all. this is an example of situational irony, where the opposite of what is expected occurs. instead of a romantic reconciliation, gatsby and daisy exchange a few pleasantries and avoid eye contact. in fact, gatsby makes a complete fool of himself, even considering walking out and not coming back.

to answer the second part of your question, i do think the weather has some impact on the ironic situation. gatsby wants his meeting with daisy to be absolutely perfect, so the rain is the first thing that puts a wrench in his vision. it also presumably causes daisy to be late, another thing that goes against his vision.

of course, the awkwardness is further cemented through their personalities. daisy is completely caught off guard, and when she feels uncertain she becomes somewhat helpless, as the reader discovers by the end of the novel. gatsby, on the other hand, is easily frustrated when things don’t go his way. therefore, the circumstances of the meeting contribute to it’s ironic atmosphere.

there are a couple of things about daisy and gatsby's meeting that might be considered ironic. one is that gatsby has been wanting to meet her again for many years and has gone to a tremendous amount of trouble and expense to arrange a meeting, and yet when they finally do meet he doesn't know what to say to her. it is ironic that such a self-reliant, successful man of the world should be so shy. the same is pretty much true of daisy. she loses her sophistication and poise at this critical moment.

the other thing that seems somewhat ironic about the meeting is that both of them are rich and live in mansions and yet they meet in a little cottage which seems even smaller because gatsby has filled it up with flowers.