 John Grimes was born in County Limerick to John and Bridget (née Hammon) Grimes.He was educated at both a national school and a Jesuit college in Ireland before going to Canada, where he enrolled at the College of Saint-Hyacinthe in 1874.Attached to the Diocese of Albany, New York, in the United States, he was sent by Bishop Francis McNierney to study at the Grand Seminary of Montreal in 1878.