Why does the south and north have opposite temperatures?

Basically because of the tilt of the Earth's axis, which can put either one of the poles closer or further away from the heat of the sun.

They Have Different Temperatures during the seasons because of the earths tilt on the axis towards the sun. When The Northern Hemisphere of the earth Is tilted towards the sun, it warms it up, but if its tilted back it will be cold, same for the south!