Eva Sweeney as Young Maureen Flavin Sweeney

Colin Wright as General Dwight D. Eisenhower

Mike Johnson as Captain James Stagg

John Downes as Met Éireann Telephone Operator

Antony Beevor as Self - Historian

Robert Gerwarth as Self - Historian

Susan Eisenhower as Self - Eisenhower's Granddaughter

Joseph Skelly as Self - Historian

Richard G. Trefry as Self - Retired US Army Lt. General

Maureen Flavin Sweeney as Self - Weather Observer (1944)

Gerald Fleming as Self - Meteorologist

David McCullagh as Self - Journalist

Catherine Ross as Self - British Met Office Archivist

Jeremy Green as Self - British Military Police Colonel

Rodney Teck as Self - Climate Researcher

John C. Sweeney as Self - Climate Researcher

Vincent Sweeney as Self - Lighthouse Keeper

Richard Callaghan as Self - Royal MP Museum Curator

Joe Cattini as Self - D-Day Veteran

Adolf Hitler as Self - Politician (archive footage)

Bernard Montgomery as Self - British Military (archive footage)

Dwight D. Eisenhower as Self - US Military (archive footage)

Éamon de Valera as Self - Politician (archive footage)

Erwin Rommel as Self - German Military (archive footage)

Franklin D. Roosevelt as Self - Politician (archive footage)

James Stagg as Self - Meteorologist (archive footage)

Joseph Goebbels as Self - Politician (archive footage)

Joseph Stalin as Self - Politician (archive footage)

Winston Churchill as Self - Politician (archive footage)