Yes. There is summer everywhere on earth, depending on location. In the southern hemisphere, summer begins on December 21.
In December 21st, that is to say in the same month winter starts in northern part of the world.
December
December 21st
Canada
In the summer the part of the Earth that is summer is closer and in the winter it is farther away.
June -- September . . . . northern Hemisphere December -- March . . . . southern Hemisphere
Summer
This is due to the tilt of the Earth and the equinoxes. During the northern summer months, the Earth's axis is tilted in a northward direction, toward the sun, and vice-versa for the southern hemisphere.
Christmas (Celebration of the birth of Jesus the Messiah) in observed on December 25th throughout the world. In the Northern Hemisphere (that part of the world globe which is above the equator) December 25th is at the beginning of Winter. In the Southern Hemisphere (that part of the world globe which is below the equator) December 25th is at the beginning of Summer. UAE is above the equator, and Australia is below the equator. When the Northern hemisphere is having Winter, the Southern Hemisphere is having Summer. The same is true in reverse, when the Northern hemisphere is having Summer, the Southern Hemisphere is having Winter. This is due to the position of the earth in relation to the sun and the tilting of the axis of the earth.
Summer!
Yes. Summer begins in the Southern Hemisphere on December 21 and fall begins on March 21.