Why are some countries hotter than others?

Since the earth is a sphere, places nearer the equation get a more direct exposure to the sun- the sun's energy is dispersed over a smaller area than occurs nearer the poles. Altitude and proximity to large bodies of water also affect the temperature. It tends to be cooler in the mountains and sea or lake breezes can cool or, in the case of the Gulf stream ,warm a region. Thermal activity such as volcanoes and geysers makes some places hotter. The humidity also has an effect- a cloud cover keeps the sun from warming so quickly and keeps the earth from cooling off so quickly at night.