Forshaw Day was born in London, England in 1831. He studied architecture and design in London at the Royal Dublin Society's School of Art and the Central Training School, Gore House, South Kensington. In 1862 he came to Halifax where he worked as a draftsman in H.M. Naval Yard, taught art students, and painted the Nova Scotian landscape.
He married Sophia Zwicker in 1863. From 1865 to 1879 his work was exhibited at showings in Canada, the United States and Europe. In 1879 he left Nova Scotia to accepted a position at the Royal Military College at Kingston, Ontario. In 1879 he joined the Ontario Society of Artists and in 1880 he was selected as one of the founding members of the Royal Canadian Academy of Arts. After 18 years of service at Kingston, Day retired in 1897 due to age and ill health. He died in Kingston in 1903.