Ask someone to picture Antarctica and they will hand you a number near forty below. However, the freezing temperatures that built Antarctica's reputation come from the high plateau, where stations have logged readings near minus 129°F. No expedition vessel goes there. You'll be on the coast, at the mild edge, and on one of the most northerly points of the continent.
The thermometer is only half the story. Two things decide how cold a day actually feels on deck or ashore:
Wind: A calm and sunny day at 32 degrees F is comfortable in a decent shell. The same temp with twenty knots blowing across an open Zodiac is a different proposition. Watch the wind, not the air reading on its own.
Water: The Peninsula is the one part of the continent where summer precipitation could arrive as rain or heavy wet snow, or even show up as fog. Staying dry does more for you than adding one more layer, so be sure that your gear is actually waterproof.
The practical lesson is to dress for wind and wet, not for a freezer. Layers you can peel off on a calm, sunny landing, under waterproofs you can trust.
