What causes January thaw?

Answer 1

January thaw refers to a period in the middle of winter when the weather typically warms to above normal. It doesn't always happen and the most logical response would be that cold weather patterns can't sustain themselves for many weeks at a time, so at some point the weather will moderate, even if just to "reload" for another long spell of cold. The weather in the mid-latitudes is always fluctuating, especially during winter, and trying to balance itself out. This is most apparent when we perceive it to warm considerably in the dead of winter.