Season of Christmas in Australia and South America

Word Meaning:

SUMMER — One of four seasons, traditionally the second, marked by the longest and typically hottest days of the year due to the inclination of the Earth and thermal lag. Typically regarded as spanning either the period between the summer solstice to the autumnal equinox, or the months of June, July, and August in the Northern Hemisphere and the months of December, January and February in the Southern Hemisphere.

Definitions from Wiktionary.