December 21 is the winter solstice in 2022. That means that the sun is the lowest in the sky and the days are the shortest of the year in the Northern Hemisphere. This year the actual time of solstice is 4:48 pm Eastern Time. You can read more about the winter solstice at EarthSky here or read about what causes the seasons from NASA here.
Normally the coldest time of year follows the winter solstice by about a month, but this year we may see the coldest period next weekend when a massive cold wave moves through the central and eastern United States. Make sure you are getting forecasts from the National Weather Service or a professional meteorologist and not just some weather nerd on Twitter! And get updates, too, because conditions can change quickly in a storm like this. Fortunately, after this weekend, warmer temperatures will return to a lot of the US.