Olympic Snowboarder Jamie Anderson's BIKINI WORKOUT ... At Vegas Pool Party

Snowboarding season is OVER ... it's time for BIKINI season -- at least according to Team USA gold medalist Jamie Anderson ... who flaunted her world-champion physique in Vegas this week.

Anderson -- who won gold in the slope-style event in Sochi -- hit up the Azure Luxury Pool at Palazzo hotel ... along with fellow gold-medalist Kaitlyn Farrington (she won gold in the half pipe).

The ladies were joined by a bunch of the women they crushed in the Olympics -- including Kjersti Buaas (snowboarder, Norway), Stefi Luxton (snowboard, New Zealand) and Rebecca Torr (snowboard, New Zealand).

FYI -- it was 89 degrees in Vegas yesterday ... it's 43 and raining in Norway.