Winter is the coldest season of the year. The Northern Hemisphere, the northern half of the earth, has winter weather during December, January, February, and early March. In the SouthelTI Hemisphere, winter weather begins in late June and lasts until early September. For dates of the first day of winter and information about the position of the earth and sun during winter.

During winter, the polar region is especially cold because the sun does not rise there for weeks or months at a time. Cold, dry air moves south from this region, blinging cold weather. Storms move from west to east along the southern edge of the cold air. In the United States, winter storms produce large snowfalls in some areas. The most snow falls in the western mountains and in much of the northern region east of the Rocky Mountains. Many winter storms bring rain to warmer southern areas. The lowest winter temperatures usually occur in the middle of all continents.