Three Days of Darkness

In Roman Catholicism, the Three Days of Darkness is an eschatological concept believed by some Catholics to be a true prophecy of future events. The prophecy foretells three days and nights of "an intense darkness" over the whole earth, against which the only light will come from blessed beeswax candles, and during which "all the enemies of the Church... will perish."
The prophecy parallels one of the Ten Plagues against Egypt in the Book of Exodus. The Apocalypse of John also mentions a plague of unnatural darkness as an effect of the fifth vial. Unnatural darkness is also associated with the sixth seal of Revelation.
However, the specifics of the "Three Days of Darkness" prophecy, such as the miraculous beeswax candles, are derived from private revelation.

Advocates

is the best-known seer associated with the Three Days of Darkness prophecy. She reportedly described the event as follows.
Marie-Julie Jahenny, known as the "Breton Stigmatist," expanded upon the story of the Three Days of Darkness. According to Jahenny, it would occur on a Thursday, Friday and Saturday; all of Hell would be let loose to strike at those outside their homes and those without a lit blessed candle of pure wax. These candles would miraculously stay aflame the entire period, but not light at all in the houses of the godless.

Padre Pio hoax

In the late 1940s, the name of Saint Padre Pio was attached to a letter endorsing the Three Days of Darkness; but the letter was in fact written by the "Council of Heroldsbach," a religious cult in Germany later outlawed by the Vatican. Since 1950 the "Pio" forgery has been repeatedly denounced by both the Capuchin order and the Archdiocese of Bamberg.

Sedevacantist views

Some sedevacantists hope that a true Pope will be miraculously designated by an apparition of Saint Peter and Saint Paul; this tangential belief assumes that the pontiffs in those times of the Church will be, in fact "antipopes".