McVittie was born on 5 June 1904 in Smyrna in Turkey, where his father, Frank S. McVittie, was a merchant. His mother, Emily Caroline Weber, lived in Greece but was of British descent.[3] George was raised bilingual in French and English.
From 1923 he studied mathematics and physics at the University of Edinburgh receiving his degree (MA) in 1928. He then went to Christ's College, Cambridge where he studied for his doctorate (PhD) under Prof Arthur Eddington.[4][5] From 1930 to 1934 he was Assistant Lecturer at the University of Leeds, 1933-34 Lecturer at the University of Edinburgh and 1936-1958 Reader at King's College, University of London. In 1933 he became a fellow of the Royal Astronomical Society, being elected in 1933. [6][7] During World War II he established and directed the meteorological section at Bletchley Park, which monitored weather conditions in enemy territory by deciphering coded weather forecasts.