Year Without a Summer
1816 is referred to as “the year without a summer” because temperatures in eastern North America and western Europe that year were significantly lower than the long term average (by 3° in France, for example). Crop failures were widespread across the northern hemisphere, and this after harvests had been poor for a number of years in the aftermath of at least five other eruptions.
The cause of the cooler temperatures was the April 1815 eruption of Mount Tambora in Indonesia. This was the most severe volcanic eruption since the one in the sixth century which caused the volcanic winter of 536.
In the years after 1815, a reddish hue was visible in the sky, the result of volcanic dust in the atmosphere.
It was during the volcanic winter of 1815 that Mary Shelley began to write Frankenstein, after she, Percy Shelley and Lord Byron had a competition to see who could write the best “ghost story”.