Evidence suggests that the anomaly was predominantly a volcanic winter event caused by the massive 1815 eruption of Mount Tambora in the Dutch East Indies ( now Indonesia ) . This eruption was the largest eruption in at least 1,300 years ( after the extreme weather events of 535 – 536 ) , and perhaps exacerbated by the 1814 eruption of Mayon in the Philippines
1815 eruption of Mount Tambora
1815 eruption of Mount Tambora
Year Without a Summer