Bartolo’s name day is August 25, the feast of Return of the Relics of Bartholomew.
Churches that follow the Old (Julian) Calendar keep the same feast on September 7 of the civil calendar. See everything commemorated on August 25.
The saint behind the name

Return of the Relics of Bartholomew
August 25, Apostle, Βαρθολομαίος
This feast commemorates the translation of the relics of the Holy Apostle Bartholomew, one of the Twelve, who preached the Gospel in eastern lands and completed his apostolic course as a martyr. According to tradition, his relics, placed in a coffin and cast into the sea by persecutors, were carried by the waves and received with honor by the faithful, coming at last to the island of Lipari.
Name days: Bartholomeos, Bartholomew, Bartolo
Also celebrating on August 25
These names share the feast, many of them other forms of the same name:
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.