On April 10, 1815, Mount Tambora erupted on the Indonesian island of Sumbawa after what some scientists believe was a period of inactivity of about 5,000 years. The massive blast shot an estimated 24 cubic miles (100 cubic kilometers) of rock and 220 million tons (199.54 billion kilograms) of sulfur dioxide almost 29 miles (40 kilometers) into the atmosphere. Everything within 400 miles (645 kilometers) of the blast was plunged into near total darkness. Tsunamis reaching 16 feet (five meters) in height crashed onto surrounding shorelines. After the initial eruption, the volcano continued to erupt through mid July.

To make matters worse, two previous volcanic eruptions also contributed to dust and debris being thrown into the Earth’s atmosphere. The volcano Soufrière St. Vincent erupted in the Caribbean in 1812, and two years later Mayon Volcano exploded in the Philippines. In addition to all this volcanic activity, there was an increase in sunspot activity, including one particularly large sunspot that was so big it could be seen with the naked eye.

All of these events conspired to lower temperatures dramatically all over the planet. Canada, Europe, and the United States were all very hard hit, particularly in the East and Midwest, where crop failures were extensive in 1816. During that summer, snow fell a few times in New England in June. Vermont saw ice on its lakes in June thick enough to skate on, while snow was as deep as 18 to 20 inches (45 to 50 centimeters) deep. After this bizarrely cold summer, the winter of 1816 to 1817 was rather mild, but that did not matter since the crops were all ruined.