Rihanna -- Enjoy Your Frozen Xmas, CHUMPS!

Here's a photo of Rihanna in Barbados ... in a bathing suit ... where she'll be spending her Christmas holiday relaxin' like a she-pimp in 81 degree weather.

FYI -- it's 36 degrees in NYC right now ... 53 and raining in L.A. ... 14 degrees in Minneapolis ... 37 in Dallas ... 52 in Atlanta ... 32 in Boise ... etc, etc, etc.