Hell freezes over headlines were made when Leonardo DiCaprio finally won the Oscar in 2016 (for The Revenant).
Susan Lucci was, for a time, the Distaff Counterpart to Leonardo DiCaprio. She was nominated for the Emmy 18 times for her role on All My Children without winning. Many made Hell freezing over jokes when she did win her Emmy on nomination #19.
It is said that before he became Emperor, Caligula met with a fortune-teller, who told him "You are as likely to rule the Roman Empire as you are to ride across the bay of Naples without getting your horse wet." When he did become emperor, he commandeered all the boats in Naples, lined them up from one side of the bay to the other, and rode his horse across them, just to spite the fortune teller.
The New Orleans Saints for the most part were one of the worst NFL teams; some exclaiming that "Pigs Would Fly" if the Saints went to the Super Bowl. However, the Saints' fortunes changed for the better and in 2010, the Saints finally got the right to play in the Super Bowl, which Saints announcer Jim Henderson then exclaimed: "Pigs have flown! Hell has frozen over! The Saints are on their way to the Super Bowl!". Later, making sure that "Pigs Were Flying" in New Orleans, the Saints would go on to win the Super Bowl.
Before Eurovision Song Contest 2006, after a Finnish metal band was announced, it was said that "Hell will freeze over before Finland wins". Finland got 292 points, at that time the highest number on record.
Perhaps ironically, the Finnish band was Lordi, which was almost not admitted due to accusations of Satanism. Definitely ironically, the song with which they won was "Hard Rock Hallelujah", which the band's "face", Mr. Lordi, used as proof that they're not Satanic.