I got extraordinarily lucky on this trip. Our guides said that on any given summer, there are 5-10 days where it's "warm" and sunny. On this trip, we had three of those days in a row! The guides were all baffled and totally overjoyed. In fact, one particularly warm day rose up to 50 degrees Fahrneheit, and we all took our layers off and hung out in our t-shirts instead!
However, after that, the weather became much more (as the guides said) "Antarctic," with snow and fog and grey skies. However, I really liked this, because it felt more moody and atmospheric.
I saw gentoo, adelie, and chinstrap penguins. I saw crabeater, Weddell, and leopard seals, plus a single baby elephant seal! I saw a fin whale and a few dolphins. I saw lots of petrels, albatross, cormorants, and sheathbills, too. There's way more wildlife than people.