This question came from Gregg from Lemont. To understand this question, you have to think about the overall energy balance. Let’s back up to looking at a simple object. If more energy is put into the object than it loses, it will warm (i.e. putting a pizza in the oven). If it loses more than gains it will cool (i.e. pizza in the refrigerator).
What causes the northern hemisphere to heat and cool is the surplus or deficit of thermal energy from the sun. What is more important than the time the sun is out, is how high it gets in the sun. If you notice in the winter, the sun is much lower in the sky than in the summer. During the lowest sun (which is around the winter solstice), the northern hemisphere is getting the least energy from the sun. However, we are still losing more than we gain. So the lowest record temperatures and the lowest average temperatures don’t come until later in January. The balance really starts to shift again in February and that’s when the records and the average start to increase once again.