I sense that Andy endures many different conflicts in the last moments of his life. He does not seem to be overtly bothered by the presence of nature in the form of rain. There are more issues that he is enduring at this point than his challenges with nature. One such conflict is with the world around him. The fact that people like the drunk man and the young couple refuse to help him, while he is pleading for his life without a voice is reflective a conflict with society that Andy is enduring. When he could have been helped, people walk past him without offering help.
I think that towards the end of the narrative, one sees Andy experiencing internal conflict. This becomes clear when he recognizes that death is unavoidable Part of this is when he recognizes that he "just wants to be Andy." His affiliation with the Royals and his wearing the jacket have caused his death, something about which he experiences some regret:
If he never did another thing, he wanted to take off the jacket. The jacket had only one meaning now, and that was a very simple meaning. If he had not been wearing the jacket, he wouldn't have been stabbed. The knife had not been plunged in hatred of Andy. The knife hated only the purple jacket. The jacket was as stupid meaningless thing that was robbing him of his life.
The internal conflict that resides with his choice of wearing the jacket is what becomes dominant in his being towards the end of his life. It is because of this that I think he experiences more of an internal conflict at the end of his life than a conflict with nature.