In Gothic literature, the weather is often used to convey the feelings and emotions of its character, in a technique called 'pathetic fallacy.' Using the weather in this way is also useful in setting the mood and developing the atmosphere in a particular scene.
In Jane Eyre, we see many examples of the weather being used in this way. In chapter one, for instance, the "cold winter" and "clouds so sombre" reflect Jane's mood and also build atmosphere in preparation for the next scene, in which we learn of Jane's "inferiority" to the Reed family with whom she lives.
Interestingly, we also see the weather used in a way which contrasts with a pathetic fallacy. When Lowood is overcome with typhus and consumption, for example, the springtime weather is portrayed as sunny and warm. Similarly, a "livid, vivid spark leapt out of a cloud" when Mr Rochester proposes marriage to Jane and this is, perhaps, an omen of the bad events which are to follow.