December.
It usually falls on either December 20th or 21st
December. The first day of winter is the solstice, usually around the 21st of the month.
Officially, winter begins with the Winter Solstice on December 21.
If you have to pick a single month, ti would be December - which is when the Winter solstice occurs. The 31 day period with the longest hours of darkness would be from 15 days before the Winter solstice to 15 days after winter solstice. The Winter solstice occurs on 21 Dec or 22 December (depending on the year). So most of that period falls within the month of December.
Earth is getting colder at that time. It does not immediately start getting warmer once the winter solstice is passed. It can be up to a month later, before it begins, so the month after a winter solstice is cold. For the summer, it is the same, in that the Earth keeps getting warmer for a time after the summer solstice, so the warmest temperatures are after the summer solstice, before the cooling process starts.
June 21st 2012
Winter is from the Winter Solstice, December 21st, to the Spring Equinox, March 20th.
Winter Solstice
No, the winter solstice marks the beginning of winter.
The Winter Solstice is actually the shortest day of the year.
The month which ends a calendar year is December. A fiscal year can end with any month, but usually with June. The Chinese calendar is based on the moon phases and ends on the day before the second dark moon after the winter solstice or occasionally on the day before the third dark moon after the winter solstice.
summer solstice and winter solstice
That depends on whether you are in the Northern or Southern Hemisphere. If you are in the Northern, then your winter solstice is the summer solstice in the Southern Hemisphere. If you are in the Southern, then your winter solstice is the summer solstice for everyone in the Northern Hemisphere.