Did you read the introduction that Mary wrote to explain how she came up with the story in the first place? She and some friends were in Switzerland. They were entertaining themselves in the midst of poor weather, and challenged one another to write a ghost story. Lord Byron, Percy Shelley, and others were there and conversing about Dr. Darwin's "survival of the fittest" theories among other scientific ideas of the time. That night, Mary had a dream that would begin the story which would be the only one to survive the ghost story challenge. Keep in mind, that the Romantics were very closely connected to nature, and that Mary uses weather and nature/natural surroundings to depict the inner conflict and moods of her characters. So, the fact that it was a "dreary night of November" indicates that the end result--the creature--was not a positive thing. November is a cold, winter month where people are often subject to bouts of depression. The choice of the word "dreary" further supports the fearful mood of the chapter. Not to mention, Victor has neglected his health and his family--two things that are important to his happiness--while embroiled in his scientific pursuits.