Since your question appears in the Dracula area, I am making the assumption that you wish to discuss the weather in that particular text. Since you also note that you want to look at it apart from plot, I will address it in terms of setting. However, in Dracula the settings and the plot are intertwined. In fact, the elements of a text really cannot be discussed as separate from one another because each element informs the greater work. That being said, weather is often used in fiction to set the mood of the story or to evoke feelings from the reader. If a story is set in a location where the weather is bright and sunny, it is less likely that the story will be filled with horror (though it is certainly not unheard of). Generally, the weather will reflect what is happening in the narrative. For instance, gloomy, stormy weather, fog, nasty temperatures, will often indicate the general mood of the tale. Changes in the weather can also indicate changes in the plot, as well. In Dracula, of course, it is not only weather that has significance, it is also time of day; sunrise and sunset are both important for both Dracula and his victims. He cannot abide the light of a sunny day, and Mina, for instance, as a victim, feels better during the daylight hours, especially if the sun is shining.