Even Thomas Jefferson noted the change in the weather. Then there are the news stories about the year (1816) without a Summer.
Mary Shelley came up with Frankenstein during the 1816 summer. She, her lover, and Lord Byron were hanging together in Switzerland bummed about the horrible weather. So to kill time they started to tell ghost stories and Mary’s would become Frankenstein.
Eighteen Hundred And Froze To Death (The Infamous 'Year Without Summer')