Why is Canada really hot in the summer, but also really cold in the winter?

Question

I understand it is cold because of the distance from the equator and so on but why does it reach 30-35 degrees C in the summer?

The Arctic remains cold all year round, even though it is right next to Canada.

Answer 1

The jet stream in the winter months drops farther south than in the summer this allows the cold arctic air to funnel southward into Canada.  In the Summer however the jet stream typically flows farther to the north allowing the warm moist Gulf of Mexico air to flow north and this warms south central and southeastern Canada.