Hermon was born on March 4, 1830, at a farm in Rednersville Township, Prince Edward County, Ontario, to parents William Hermon and Sarah Roblin. He had 8 siblings. His paternal grandparents were "Pennsylvania Dutch," and immigrated to Canada in the 1770s, while his maternal side were United Empire Loyalist settlers. Hermon went to school at Queen's University in Kingston, Ontario. He went on to teach school and eventually train and qualify as a Provincial Land Surveyor. He set up practice in the Counties of Hastings and Prince Edward. From 1882 to 1884, he was employed as Inspector of Dominion Lands Survey.
His first wife was Anne Louise Bolton of York, Ontario (m. 11 May 1861), by whom he had two children, Ernest Bolton and Robert. After her death in 1867, he married Olive A. Jeffs the following year. They had three children: Edward William, Royal Ridley and Roblin Compton. After the passing of his second wife in 1875, he remarried once again. This time he was wed to Mary Doan and produced two more children: Mary Gertrude and Bartle Pierre. After a long and prosperous life, Hermon died of "surveyors stomach trouble" on February 9, 1907, at the farm where he was born 77 years earlier.