The pattern is fixed by the 1917 apparitions, which took place on the 13th of May, June, July, September, and October, with the August apparition on the 19th at Valinhos. The Shrine keeps the 12th and 13th of each of those months as anniversary pilgrimage days, and May and October draw the largest crowds; the Shrine reported about 470,000 pilgrims on May 12 to 13, 2025 and close to 180,000 in the prayer area for the International Mass on May 13, 2026, which the Patriarch of Lisbon presided.
The shape of the two days is the same each time: on the evening of the 12th the rosary in several languages, the candlelight procession with the statue of Our Lady carried through the prayer area, and a celebration of the Word; on the morning of the 13th the rosary, the International Mass, the blessing of the sick, adoration, and the farewell procession returning the statue to the Chapel of the Apparitions. The Shrine publishes exact hours for each pilgrimage on its schedule page shortly beforehand; the hour of the International Mass is not on the daily schedule, so check it for your month.
For 2027 the calendar gives May 12 to 13 and October 12 to 13 as the international pilgrimages and the 12th to 13th of June through September for the others, but presiders and hours are not published on the official site; confirm there before booking. On the ordinary 13ths the Shrine also celebrates a 3:00 p.m. Mass for benefactors.