I have always understood this to be a compromise between the longest night and the coldest days, sure in late January it is colder, but you can tell that the da

I have always understood this to be a compromise between the longest night and the coldest days, sure in late January it is colder, but you can tell that the days are getting longer, the effect is more pronounced the farther north you are, and remember that the southernmost part of the British isles is north of the lower 48