Maybe there’s no particular reason, but it has always struck me as odd that it would be “that close” to the winter solstice, yet not actually be on the winter solstice.
It seems the natural choice for New Year’s would be a solstice or an equinox. I’m guessing it might have something to do with an error carried over when the switch was made from the Julian calendar to the Gregorian calendar, but that’s only a guess, which is why I’m asking this question.
Going through Wikipedia it appears that originally the new year was March 1st and then three months were added at the end of the year (January, February, and Mercedonius.) and then these later were swapped about to be the beginning.
So, March 1st is the first day of “meteorological spring”, which I guess would be the reason that was chosen for the beginning of the year. And January first is 60 days previous to March 1st because it is two months previous.
We used to use March 25th as New Year’s Day, ISYN. It was one of the four “Quarter Days” (Lady Day; Midsummer’s Day, Michaelmas Day and Christmas Day were the others). Lady Day was the day for settling tax bills. When we switched over to the Gregorian calendar in England, we dropped eleven days from the calendar to realign all the equinoxes and solstices. So as to keep the current tax year to 365 days, we adjusted “Tax Day” by eleven days in the other direction to compensate, and so the end of the tax year is now April 5th.
Part of the difficulty in answering this question lies in the fact that, in much of the Western world, January 1 became New Year’s twice–once under the Romans, and again under later European governments.
As others have noted, January 1 became established as the beginning of the Roman year long before Julius Caesar, at a time when the Roman calendar was still lunar-solar. Under a lunar-solar calendar, the months can’t be exactly lined up with the seasons. The insertion of intercalary months was manipulated for political reasons, so even approximate synchronization was lost.
When Julius established a solar calendar, he retained January 1 as the beginning of the year, and he had to set it someplace relative to the seasons, with the intention that it would thereafter remain fixed. Perhaps the solstice would have been a logical point, but Julius chose to set January 1 so that the vernal equinox would fall on March 25, as it allegedly had during the time of a much earlier Roman king Numa. This is about as profound a reason as one can give for the current location of January 1 relative to the seasons.
After the fall of Rome, Christians retained the Julian calendar, but many countries gradually drifted away from January 1 as New Year’s. It’s hard to identify a single reason for the drift; religious reasons and earlier local customs undoubtedly played a part.
Then, beginning in the late Middle Ages, Western Christianity began drifting back to January 1. Some of the later countries to switch (especially the British Empire, which switched in 1752) made the change as part of the conversion from the Julian to the Gregorian calendar. It was not so in all countries, however, and the papal bull establishing the Gregorian calendar was resolutely silent as to New Year’s. No doubt synchronization of calendars for purposes of international trade played a part in the reconversion, and once January 1 attained a “critical mass” of adherents, holdout countries were more inclined to get on board.