Winter typically begins around December 21st in the Northern Hemisphere, marked by the winter solstice, and around June 21st in the Southern Hemisphere. The exact start date can vary depending on whether you refer to astronomical or meteorological definitions.
According to Wikipedia, winter is the coldest and darkest season occurring after autumn and before spring, with its start linked to Earth's axial tilt and position relative to the Sun [1]. In the Northern Hemisphere, winter generally begins around December 21st or 22nd, coinciding with the winter solstice, which is the shortest day of the year and marks the official start of astronomical winter [4]. Conversely, meteorological winter in the Northern Hemisphere starts on December 1st and ends on February 28th or 29th, based on calendar months, for easier statistical analysis [3]. In the Southern Hemisphere, winter begins around June 21st, also aligned with the winter solstice, and ends around September 22nd or 23rd [1]. It's important to note that in Australia, for example, the seasons are opposite to those in the Northern Hemisphere, with winter occurring from June to August [2]. The precise start date can vary slightly depending on whether one uses the astronomical definition (based on solstices and equinoxes) or the meteorological definition (based on calendar months). The winter solstice, which is the shortest day of the year, typically occurs around December 21st or 22nd in the Northern Hemisphere and June 20th or 21st in the Southern Hemisphere [4].