Answer:
At the end of December, all of the Southern Hemisphere is in summer.
Step-by-step explanation:
Summer is one of the four seasons of the temperate zones. It is the warmest of them. It follows spring and precedes autumn. Summer is characterized by the days are longer and the nights are shorter. Astronomically, the summer solstice, which occurs on December 21 in the Southern Hemisphere, marks the beginning of this season, and the autumn equinox, which occurs on March 21 in that hemisphere, marks the end of this season and the beginning of autumn.