Question

This is science - Which is hotter the southern or the northern

Answer 1

No, the northern hemisphere summer is hotter when you look at the planetary average. The reason is that there is more land in the northern hemisphere and when the sunlight hits the land it bounces off and heats up the air much more than when sunlight hits water. So whichever side with more land will have a hotter average summer, in the earth's case, by about 4 degrees Farenheit.
On the other hand, the amount of water in your local environment has a much greater influence on the heat of your summer than which hemisphere you're in. For more detail, check out NASA's explanation below.

Answer 2

Southern hemisphere is warmer than northern hemisphere while south pole is cooler than north pole. The average annual temperature in southern hemisphere is higher.

Answer 3

The Southern of the Northern what?