"Rogation Days" In Catholic Encyclopedia: https://www.newadvent.org/cathen/13110b.htm
Days of prayer, and formerly also of fasting, instituted by the Church to appease God's anger at man's transgressions, to ask protection in calamities, and to obtain a good and bountiful harvest
plugging c/sede as well
I don't think the post-Vatican 2 movement observes these as much anymore, maybe the "fssp / indult" people do though