After finishing his secondary education there, he completed a building apprenticeship and at the same time studied mathematics, physics and geology part-time.
He then moved to Dunedin, and studied at the University of Otago, from where he graduated with a Bachelor of Science in 1951. Hickman joined the New Zealand Meteorological Service, rising to become its director in 1977. He remained in that role until his retirement in 1988.
He served as vice-president of Regional Association V of the World Meteorological Organization from 1982 to 1986, and president from 1986 to 1988.
Hickman also served as the convenor of the climate committee of the Royal Society of New Zealand until 1994. He died in 2014.
He was also awarded the New Zealand 1990 Commemoration Medal, and in 1998 he was made an honorary member of the Meteorological Society of New Zealand.