Winter timing depends on the definition used:
- Astronomical winter begins at the winter solstice and ends at the spring equinox. In the Northern Hemisphere, this is typically from December 21 or 22 to around March 19 or 20. In the Southern Hemisphere, it runs from around June 21 to September 22.
- Meteorological winter is defined by calendar months with the lowest average temperatures. It includes December, January, and February in the Northern Hemisphere, and June, July, and August in the Southern Hemisphere.
Thus, winter usually falls between December and February in the Northern Hemisphere and June to August in the Southern Hemisphere by meteorological reckoning, while astronomically it is from solstice to equinox, roughly late December to late March or late June to late September depending on the hemisphere. Winter marks the coldest and darkest season of the year for its respective hemisphere.
