Tambora sits on Sumbawa Island, east of Java in what is today Indonesia. Geological evidence shows it probably hadn't erupted in 5,000 years....The big show began April 10. Three columns of fire were seen towering into the sky. By the next day Tambora had ejected about 12 cubic miles of magma into the air.But the mountain's solid towering peak was also gone. The eruption left a deep summit crater, with a rim 4,100 feet lower than the peak had once been. People in Surabaya, 300 miles away on Java, felt the earth move — possibly the result of the caldera collapse. Between the magma ejected from below and the pulverized mountaintop above, Tambora sent more than 36 cubic miles of pulverized rock into the atmosphere. The ash falling on islands nearby immediately suffocated crops. That alone probably killed 92,000 people.
The cloud of ash that was fine and light enough to stay in the atmosphere circled the globe. Average temperatures dropped as much as 5 degrees Fahrenheit over the next year ... and beyond. Many Europeans and North Americans called 1816 the "year without a summer."
In elementary school, we had a story on it in our reading books. IIRC the title was "Eighteen-Hundred and Froze-to-Death."
Snow fell in New England and Eastern Canada in June. (Quebec City got a foot of the stuff.) Frost was recorded in each of the summer months. Drought struck in July and August, and the sunlight was weak. Crops were stunted or failed entirely. Much of what survived and looked near to harvest was killed off by a September frost.