Celebration, of course, was the reason why he'd picked the place they landed. A celebration somewhere he had never been before, so it would be a treat to both him and his companion.
Reinette's health was doing significantly better than he'd originally expected it to, and that meant celebration. Right, so it was a rather flimsy excuse for a celebration, but the Doctor did so love to celebrate. In this case, it was a celebration somewhere her health might not have allowed her before: somewhere cold. He tugged on a shorter version of his fourth self's scarf and his jacket as he waited for his companion to join him.
"Right, make sure your shoes have decent traction!" he called over to her.