Katherine Elizabeth Dewar was born on 13 November 1943 in Summerside, Prince Edward Island, the daughter of Robert and Mae (Profitt) Dewar. In 1963 she graduated from Prince of Wales College with an honours degree and the Samuel N. Robertson Memorial Scholarship. Following marriage and the birth of two children, Christopher and Paul Snively in Ontario, she returned to Prince Edward Island in 1968 and entered the diploma programme at the Prince County Hospital School of Nursing. In 1972, following graduation the previous year at the top of her class, Katherine became a nursing instructor with the Prince Edward Island School of Nursing, a career which spanned the next twenty-two years.
Throughout her career she continued to study, attaining a Bachelor of Arts in Sociology from the University of Prince Edward Island and a Masters in Adult Education from St. Francis Xavier University in Antigonish, Nova Scotia. She was active in her professional association locally, provincially, and nationally and in 1987 received the Association of Nurses of PEI scholarship.

Katherine's interests include painting in oils and acrylics, sailing, genealogy, and historical research. She served on the Summerside Yacht Club executive, was President of the PEI Sailing Association, and sat on the board of the Canadian Yachting Association. Katherine is also a social and environmental activist, with an interest in environmental health issues. Katherine has contributed articles to "The Island Magazine" and authored the books "Deoradh: The Dewars: Storytellers and Relic Keepers" (1997), “Islanders in the Spanish-American War of 1898 and the Philippine-American War of 1899-1902: An Out-Migration Story” (2012), and “Those Splendid Girls: The Heroic Service of Prince Edward Island Nurses in the Great War” (2014), as well as coauthoring "This Caring Place: The History of the Prince County Hospital and School of Nursing" (2001) with Wayne Wright. Katherine has received several heritage awards for research and writing, including the PEI Museum and Heritage Award of Honour, given for an outstanding contribution to the heritage of PEI over a long period of time.