During the Dark Ages, when knights would dawn their majestic arm, they would wear cotton robes underneath for comfort. The same basic concept has been adopted today when snowboarders dawn baselayers to keep them warm, only cotton is out. For a baselayer that will keep you warmer then the Mexican Riviera, check out the 686 Rings Base Layer Bottoms.
92% Polyester / 8% Lycra "Toptech" jersey knit face with bonded brushed microfleece inside
Toptech The heaviest weight of 686's technical base layer garments with 330 g insulation
An antimicrobial finish to guard against odor causing bacteria/fungi
30+ UPF guard