The winter solstice is the solstice that occurs in December. The wintertime meeting between the gods of Olympus is held during the solstice. It is the darkest day of the year which usually occurs on December 21 or 22. The winter solstice is the day of the year when ancient, evil magic is at its strongest. This is the only time when Hades can visit Olympus because this is when the gods need strength in numbers.
During the winter solstice, the Master Bolt was stolen from Zeus by Luke Castellan. Luke was on Mount Olympus with some campers from Camp Half-Blood, so he had an alibi. He snuck into the throne room and stole the Master Bolt from Zeus and the Helm of Darkness from Hades. He found the theft incredibly easy, stating "The Olympians are so arrogant; they never dreamed someone would dare steal from them."
Percy, Thalia, and Grover manage to rescue Artemis, and she brings them to Mount Olympus, just in time for the voting. The gods vote in favor of action, not destroy the Ophiotaurus, and not destroying Percy and Thalia. At this meeting, Thalia joins Artemis' Hunters, partially in order to escape from the Great Prophecy as her 16th birthday was the next day.
Strangely, Hades is not present, even though the winter solstice is the only time of the year he is allowed to visit Olympus.
- In The Titan's Curse, Hades was not present at the winter solstice meeting.