Obviously the Sun is the source of our heat, but the Earth itself has factors which cause the amount of sunlight that reaches the Earth to vary. Our distance from the sun varies, but this does not account for the temperature variation. During our summers in the northern hemisphere, we are farthest from the sun, but are tilted toward it. The Earth is tilted on its axis 23.5 degrees, which results in the northern and southern hemispheres being tilted toward the sun at times, and away from the sun at other times. Continentality, the aspect that allows more extreme temperature variations near the center of a continent far away from a water mass, is another important consideration.
Volcanic eruptions can cause weather disturbances also.
Knowing what factors influence temperature might give us a clue in our search for the coldest spot on Earth. The United States alone has recorded some impressive and bone chilling colds. The lowest average winter temp for the US is -15.6 F on Alaska s Barter Island. There are quite a few places, such as Russia, Switzerland, and Norway, which can top those average winter temps. We certainly have no problem envisioning lots of snow, year round, cold wind blowing.