I believe we only have about 8 weeks of true winter. From mid Dec to around 10th Feb. Usually, we can rely on double digit (and mins this season!) until mid Dec, and I've always thought there is a perceptible change come around about 10th Feb. This is due to the level of light, and solar height. It just feels like spring from around mid Feb onwards, regardless of most temperatures. Certainly here in the South West, anyhow! Maybe not in Aberdeen...