February is when the wildlife stops posing and starts behaving. Chicks are off the nest, muddy and running around with parents chasing them. Leopard seals move into the shallows as the first chicks start swimming late in the month. Whales become properly interactive rather than distant. The Antarctic Circle also becomes more reachable as the ice retreats, so Circle itineraries cluster from here on.
The trade is that colonies get muddier and less photogenic as the month goes on, and chick numbers start thinning.
This is where the season's character shifts. Up to about mid February the trip is built around penguin colonies. After that it's increasingly about whales and predation, and which of those you prefer should drive your booking more than temperature or price does.
Pricing starts easing in late February, which is the beginning of the best value window of the year.