Nugent Herrmann Welch was born at Akaroa on 30 July 1881, the third child and second son of Isabel Nugent and her husband, Joseph Sandell Welch, an assistant surveyor. In 1893 Joseph accepted a position as senior draughtsman with the Department of Lands and Survey and the family moved to Wellington. Influenced by his father, an amateur artist, Nugent was interested in art from an early age. He was educated at Newtown School, and probably attended evening classes in art at the Wellington Technical School, taught by Arthur Riley, James Nairn and others. In 1895 and 1896 he passed first- and second-grade drawing examinations run by the technical school. In September 1897 he became a clerk in the accounts branch of the Wellington Harbour Board. He disliked routine office work, however, and in December 1907 resigned to become a full-time artist.
Welch initially worked from his family's home in Wright Street, Mount Cook, before taking a studio in Boulcott Street. He first exhibited at the New Zealand Academy of Fine Arts (NZAFA) in 1904. After Nairn's death that year, Welch became an influential figure in Wellington art circles. He helped to revive the Wellington Art Club in 1906, and regained the use of Nairn's Pumpkin Cottage at Silverstream as a painting retreat.
The First World War interrupted Welch's career. He enlisted in March 1916 and served with the 2nd Battalion, New Zealand Rifle Brigade, on the western front. In October 1917 he was promoted to lance corporal, and in April 1918 he was appointed divisional war artist with the temporary rank of sergeant. His simple landscapes, which often featured ruined buildings and seldom included people, portrayed the desolate aftermath of battle.
Discharged from the army in May 1919, Welch resumed his art career, again working from a studio in Wellington's Boulcott Street. The same year he became a member of the council of the NZAFA, a position he held until 1928 and again from 1932 to 1948. From 1936 to 1964 he was a member of the management committee of the National Art Gallery. For the gallery's opening in 1936, Welch was commissioned to paint a large canvas of Wellington Harbour; it was later displayed at Government House.
The countless changing patterns of sky, sea and land fired Nugent Welch's imagination and were the primary subject matter of his work. He painted throughout New Zealand but devoted most of his attention to the lower North Island, particularly Wellington's rugged coastline. Cape Terawhiti was one of his favourite painting locations. During the 1930s he regularly tramped for three hours to Oteranga Bay, where he would paint by day and spend nights in a cave furnished with wood from the beach.
Welch worked in both oils and watercolours, but his standard format was the medium-sized watercolour, either painted on the spot or worked up later from sketches. He skilfully blended sky and land into well-balanced compositions underpinned by closely related tonal ranges. His images are distinguished by their emphasis on the forms and shapes of the water and landscape, and by his subtle and understated control of the medium.
A hip injury caused by a fall forced Welch to give up his studio in 1964, but he continued to exhibit at the NZAFA for several years. He had never married, and lived at his family's Mount Cook home until 1967, when he and his sister Jessie moved into a rest home. After his death, at Wellington on 16 July 1970, Welch's ashes were scattered at his beloved Cape Terawhiti.
Nugent Welch was a lean, athletic man, over six feet tall, with thin fair hair and grey eyes. A keen tramper and swimmer, he was described as 'an outsize Peter Pan in shorts'. He combined a love of the outdoors with an accomplished – if conservative – painting style, and became one of New Zealand's best-known landscape artists. His contribution to the affairs of the NZAFA and the National Art Gallery was recognised when he was made an OBE in 1949. Welch's paintings are held at the Museum of New Zealand Te Papa Tongarewa, National Archives, and in other public and private collections.