The volcano, Mount Tambora, erupted in 1815, which led to 1816 now being known as "The Year Without a Summer." This eruption caused constant rain, storms, and dark gloomy skies all through Europe. During this time, Mary Shelley was staying in Switzerland. Because of how bad the weather was, Mary Shelley, Lord Byron, and a few other writers ended up being stuck indoors and told ghost stories to pass the time. The ghost stories is what inspired Mary Shelley to take on writing Frankenstein. In The Year Without a Summer, the world was described as dark, cold, stormy, and unpredictable. These same qualities are found in Mary Shelley's Frankenstein. The iciness, storms, and "gloominess" of the novel is supposed to represent the fear and uncertainty that people felt during this timeframe.
Mönch am Meer - Alte Nationalgalerie in Berlin by Caspar David Friedrich is licensed under Public Domain.
Steinberg, Michael, "The Year Without a Summer: Mount Tambora Volcanic Eruption." The Old Farmer's Almanac, https://www.almanac.com/year-without-summer-mount-tambora-volcanic-erup…