Snow was born in Dublin, the son of Brigadier J. F. Snow, CBE. He is the grandson of First World War general Sir Thomas D'Oyly Snow; cousin of Jon Snow, the presenter of Channel 4 News; nephew of schoolmaster and bishop George D'Oyly Snow; and brother-in-law of historian-writer Margaret MacMillan. Also, he is the father of fellow TV presenter Dan Snow.
He spent part of his early childhood in Benghazi, Libya, where his father was stationed. His father became deputy Fortress commander at Gibraltar in 1956.
Snow was educated at Wellington College, an independent school in the village of Crowthorne in Berkshire, and subsequently read Greats at Balliol College, Oxford University, where he was taught by classicist and ancient historian Russell Meiggs and moral philosopher R. M. Hare. From 1956 to 1958 he did National Service as a 2nd Lieutenant in the Somerset Light Infantry, serving in Plymouth and Warminster.
Snow was a foreign correspondent, Defence and Diplomatic Correspondent, and occasional newscaster for Britain's Independent Television News (ITN). He also appeared as an election analyst and co-presenter of ITN's General Election programmes throughout the late 1960s and 1970s. He joined the organisation in 1962. He gained a much higher profile after he was recruited in 1979 to be the main presenter of the new late evening BBC 2 in-depth news programme Newsnight, which began almost a year later than planned, in January 1980. He left Newsnight in 1997 and presented Tomorrow's World (with Philippa Forrester) and the BBC Radio 4 quizzes Masterteam and Brain of Britain, amongst other projects. At the Royal Television Society in 1998 Snow won the Judges’ Award for services to broadcasting.
Snow has been involved as an election analyst and co-presenter in the live General Election results programmes for many years, first at ITN for five General Elections (1966 - 1979 inclusive) and later at the BBC for a further six (1983 - 2005 incl.). He presented in-depth statistical analyses of the election results at both ITN and the BBC, and at the BBC took over responsibility for this in 1983, following the death of Robert McKenzie, and became largely associated with McKenzie's famous BBC "Swingometer" when it was reinstated in 1992. He is known for his somewhat excitable style of presentation and ever-more elaborate props and graphics, though perhaps his most famous prop was the most basic - a sandpit which he used to illustrate the progress of the First Gulf War in early 1991. In 1994, he parodied his election role by providing analysis of the entries for the Eurovision Song Contest in the BBC's two contest preview shows ahead of the final in Dublin. His data analysis predicted that either France or the United Kingdom would win. They finished 7th and 10th respectively.
Snow survived a plane crash at Port Blakely, Bainbridge Island, Washington on 1 October 1999 when the De Havilland DHC-2 Mk1, registration number N9766Z in which he was a passenger hit trees during a film project for the BBC.
Along with his son, Dan, Snow presented a TV series Battlefield Britain, covering battles on British soil from Boudicca's struggle with the Romans to the Battle of Britain. They demonstrated the hardships that the much smaller soldiers must have faced (Peter is 6'5" and Dan is 6'6"). They reunited to host 20th Century Battlefields for BBC 2 and the Military Channel in 2006. This covered battles all around the world from the Battle of Amiens in the First World War in 1918 to the Gulf War of 1990-1, and was presented in similar fashion to the first Battlefield Britain. Peter and Dan Snow authored BBC books with the same titles to coincide with the TV shows.
Peter and his son Dan also presented "Whose Britain is it anyway?", a survey of the ownership of Britain’s countryside, in 2006, "What makes Britain rich?" in early 2007 and "What Britain earns" in 2008. Peter and Dan have also made two history series for BBC Radio Four on the Black Prince, on Wellington’s Peninsular War, and the story of the Royal Flying Corps. He also presented "Random Edition" over a number of years, a Radio Four programme that examined in detail the stories in a newspaper chosen at random from one day in history.
On 6 October 2005, the BBC announced that Snow would cease working on election broadcasts. Snow himself is quoted as saying "I shall be over 70 at the next general election and that, frankly, is a bit old to be dancing around in front of huge graphic displays." In July 2006 Snow presented "Pompeii Live" for Channel Five TV, a live outside broadcast telling the story of the Roman towns of Pompeii and Herculaneum.
In January 2008, while presenting What Britain Earns, a BBC programme about salaries in the UK alongside his son, Snow admitted to earning around £100,000 a year.
In August 2008 Snow appeared in the reality TV talent show-themed television series, Maestro on BBC Two.
In July 2009, to coincide with the 40th anniversary of the NASA moon landings, ITN produced five special 10-minute programmes for ITV1 titled Mission to the Moon - News from 1969. Snow participated in these programmes, acting as a correspondent alongside former ITN colleague John Suchet, the presenter of the specials. Snow also presented a special on BBC Radio 4 focusing on "Britain's First Day of War in 1939". In June 2013 Snow presented "D-Day As it Happens" for Channel Four TV.
On the show Horrible Histories, there is a regular sketch in the section 'HHTV News' featuring Bob Hale, a character whose personality is similar to that of Peter Snow. He is known for his catchphrases 'But not for long!' and 'Or so we thought!' and usually concludes with a summary but then starts talking more.
Snow has written a number of books besides the ones written with his son, Dan. In 1970 he wrote “Leila’s Hijack War” with a journalist colleague, David Phillips, - a fast paper back telling the story of the international crisis that was caused by the Palestinian guerrillas, including Leila Khaled, who hijacked three airliners and blew them up on a desert airstrip. In 1972 he wrote "Hussein", the Biography of King Hussein of Jordan. In 2010 Snow published "To War with Wellingon", the story of the Iron Duke's campaigns from Portugal to Waterloo. In 2013, he published "When Britain burned the White House", the story of the 1814 British invasion of Washington. In 2015 he published "The Battle of Waterloo Experience" together with his son Dan on the occasion of the bicentenary of the Battle of Waterloo in June 1815. In 2016 they went on to write "Treasures of British History,The Nation's History told through its 50 Most Important Documents".
In July 2016, Snow presented Trainspotting Live - a three part television series about trains and trainspotting on BBC Four.
Snow has been married twice, and has six children from three relationships. His eldest son, French citizen Matthieu, was born before his first marriage, although Snow was not aware of his existence until he was an adult. He married Alison Carter in 1964 and the couple had a son (Shane) and a daughter (Shuna). They divorced nine years later.
In 1976 Snow married Ann MacMillan (of the Canadian Broadcasting Corporation since 1981), with whom he has a son, (Dan, who is married to the daughter of the 6th Duke of Westminster), and two daughters, Rebecca and Kate. His wife and sister-in-law are great-granddaughters of former British Prime Minister David Lloyd George.
Snow was appointed CBE (Commander of the Order of the British Empire) for his services to broadcasting in the 2006 Queen's New Year's Honours List.
His hobbies include model railways, and he has an OO gauge layout installed in his loft.
In August 2014, Snow was one of 200 public figures who were signatories to a letter to The Guardian opposing Scottish independence in the run-up to September's referendum on that issue.Peter Snow and David Philips, Leila's Hijack War. Pan Books, 1970, ISBN 345-02188-6-095
Peter Snow, Hussein, a Biography. Barrie and Jenkins, 1972, ISBN 0-214-65426-5
Peter Snow, Dan Snow, Battlefield Britain: From Boudicca to the Battle of Britain, ISBN 9780563487890
Peter Snow; Dan Snow (2007). 20th Century Battlefields. Ebury Publishing. ISBN 978-1-4481-4059-6.
Peter Snow To War with Wellington: From the Peninsula to Waterloo, John Murray, 2010, ISBN 9781848541030
Peter Snow When Britain Burned the White House: The 1814 Invasion of Washington. John Murray, London; St. Martin's Press, U.S., 2013, ISBN 978-1-4668-4894-8
Peter Snow and Dan Snow, The Battle of Waterloo Experience, Andre Deutsch, 2015, ISBN 9780-233-00447-1
Peter Snow and Dan Snow, Treasures of British History,The Nation's History told through its 50 Most Important Documents. Andre Deutsch, 2016 ISBN 9780-233-00218-7