The 1999–2000 South Pacific tropical cyclone season was an event in the annual cycle of tropical cyclone formation and ran from November 1, 1999, to April 30, 2000, in the South Pacific.

The 1999–2000 Australian region cyclone season was a slightly above average tropical cyclone season. It ran from 1 November 1999 to 30 April 2000. The regional tropical cyclone operational plan also defines a "tropical cyclone year" separately from a "tropical cyclone season", with the "tropical cyclone year" for this season lasting from 1 July 1999 to 30 June 2000.