Year Without a Summer

Year Without a Summer
1816 summer temperature anomaly compared with average temperatures from 1971 to 2000
Volcano	Mount Tambora
Start date	Eruption occurred on 10 April 1815
Type	Ultra-Plinian
Location	Lesser Sunda Islands, Dutch East Indies (now Republic of Indonesia)
Impact	Caused a volcanic winter that dropped temperatures by 0.4–0.7°C (or 0.7–1°F) worldwide

The year 1816 AD is known as the Year Without a Summer because of severe climate abnormalities that caused average global temperatures to decrease by 0.4–0.7 °C (0.7–1 °F).^[1] Summer temperatures in Europe were the coldest of any on record between 1766 and 2000,^[2] resulting in crop failures and major food shortages across the Northern Hemisphere.^[3]

Evidence suggests that the anomaly was predominantly a volcanic winter event caused by the massive 1815 eruption of Mount Tambora in April in the Dutch East Indies (modern-day Indonesia). This eruption was the largest in at least 1,300 years (after the hypothesized eruption causing the volcanic winter of 536); its effect on the climate may have been exacerbated by the 1814 eruption of Mayon in the Philippines. The significant amount of volcanic ash and gases released into the atmosphere blocked sunlight, leading to global cooling.

Countries such as Great Britain, Ireland, and France experienced significant hardship, with food riots and famine becoming common. The situation was exacerbated by the fact Europe was still recovering from the Napoleonic Wars, adding to the socio-economic stress.

North America also faced extreme weather conditions. In the eastern United States, a persistent "dry fog" dimmed the sunlight, causing unusual cold and frost throughout the summer months. Crops failed in regions like New England, leading to food shortages and economic distress. These conditions forced many families to leave their homes in search of better farming opportunities, contributing to the westward expansion.