In the spring and summer of 1815 , a persistent " dry fog " was observed in the northeastern United States . The fog reddened and dimmed the sunlight , such that sunspots were visible to the naked eye . Neither wind nor rainfall dispersed the " fog " . It was identified as a stratospheric sulfate aerosol veil . In summer 1816 , countries in the Northern Hemisphere suffered extreme weather conditions , dubbed the " Year Without a Summer " . Average global temperatures decreased by about , enough to cause significant agricultural problems around the globe . On 4 June 1816 , frosts were reported in the upper elevations of New Hampshire , Maine , Vermont , and northern New York . On 6 June 1816 , snow fell in Albany , New York , and Dennysville , Maine . Such conditions occurred for at least three months and ruined most agricultural crops in North America . Canada experienced extreme cold during that summer . Snow deep accumulated near Quebec City from 6 to 10 June 1816
Year Without a Summer
Year Without a Summer
1815 eruption of Mount Tambora