I saw a blog title today using the phrase above, annus horribilis (which the writer mispelled by using two l’s), and I had to go look it up. Not even I know everything. LOL
To my rescue came a handy site named Phrase Finder.
Turns out that annus horribilis is annus mirabilis–"year of miracles"–turned on its head to mean "year of horrors." It was popularized in 1992 by Queen Elizabeth II.