Remarkables ski area manager Ross Lawrence said July marked the quarter-century milestone of the field opening to crowds of skiers who donned multi-coloured one-piece outfits and used long, straight skis.
The 1980s-themed party would include a Chinese downhill competition, which used to be an annual fixture on the Remarkables calendar.
Competitors will race from the top of the Alta chair to the bottom, finishing in the base building.
Children will also be included in the fun, with free face-painting and a bouncy castle from 11am to 2pm and a chance to take part in a giant musical chairs competition on the beginner area.
Mr Lawrence said for the young and young at heart there would be a free AJ Hackett horizontal bungy and a "gelandesprung" - an "old school" European ski jumping competition which featured at several Remarkables events in the early days.
Prizes would be offered for the best '80s outfit and in the spirit of "best '80s entertainment", Kiwi rocker Jordan Luck would be blasting anthems from 2pm with the Jordan Luck Band.
Mr Lawrence said the birthday party, scheduled for Sunday, was about celebrating how far the Remarkables had come and showing appreciation to the many long-standing staff members who had contributed so much to the mountain.
Several people who were working at the Remarkables on its opening day were still working for NZSki.
They included Judy Stevens-Dickerson, who was still at the skifield, Hamish McCrostie, now Coronet Peak Ski Area manager, and Duncan Smith, who is on the NZSki board of directors.
A "former key staff" party would be held on Saturday where Mr Lawrence expected to see some old faces again and reminisce.
Festivities begin at 9am on Sunday, with free transport for all customers from the Snow Centre.
Entrants for the Chinese downhill competition and the gelandesprung could register on the day at guest services, until 10.30am.
