Sweet Sixteen is one of the best apple varieties for the north country - when grown on suitable rootstocks it is a reliable cropper in zone 4 and even zone 3.
Sweet Sixteen inherits its cold-hardiness from both its parents. Northern Spy is a well-known cold-hardy apple, and it is also descended from a more obscure north country variety called Malinda.
The bright red apples have a high quality flavor, primarily sweet but with some acidity and complexity. They keep fairly well in natural cold storage or a fridge.