The article linked below, by a Catholic clergyman, presents a thesis involving three October 13ths:

October 13, 1884: After taking communion, Pope Leo XIII has a vision or locution in which he witnesses a conversation between God and Satan in which Satan challenges God by saying that he could destroy the Church if he had the time, and the power. He asks God for 100 years to test the Church, and God permits it--most likely for His own honor and glory.

October 13, 1917: The final apparition of Mary to the three children takes place at Fatima, with thousands in attendance, who witness "The Miracle of the Sun". The thesis of the article is that this was also the time chosen by Satan to start his 100-year plan to destroy the Church, exactly 33 years after Pope Leo's vision, perhaps in mockery of the 33 years of Christ's life.

Then we come to...

October 13, 2017: When Satan's 100-year plan would end(?), and what progress he appears to have made in destroying the moral structure of civilization! Contraception, acceptance of sterilizations, abortions, genocide, euthanasia, assisted suicide, collapse of the family, homosexual marriages, and most recently, "gender dysfunction." In the few months left, do we time to atone for any of this? Are we in for a major chastisement?

(Not mentioned in the article: Is it a mission of Trump to attempt to reverse some of these abominations? Is that why prognosticator Paul Guercio sees Trump possibly acting as President for as little as 6 to 15 months? After which, it will be too late?)

This long article contains much more detail:

Fatima and the “signs of the times” need a closer look
January 20, 2017 by Fr. Regis Scanlon, OFMCAP
http://www.hprweb.com/2017/01/fatima-and-the-signs-of-the-times-needs-a-closer-look/