McCaskill lived at
Seer Green, near
Beaconsfield in
Buckinghamshire. He had two daughters with his first wife Lesley Charlesworth, to whom he was married from 1959 until her death from breast cancer in 1992. In 1998, he married Pat Cromack, becoming stepfather to her two sons. McCaskill was a fellow of the
Royal Meteorological Society. In May 2000, he opened the first phase of the £1.2 million
Lower Leas Coastal Park in
Folkestone. McCaskill was diagnosed with dementia in 2011 and died, in a nursing home in
South Milford, on 10 December 2016, aged 78. ==Books==