The Earth's orbit around the sun is not a perfect circle, but rather an ellipse. As a result, the distance between the Earth and the sun varies throughout the year. The point at which the Earth is closest to the sun is called "perihelion," and it occurs around January 3rd.
At the same time, the northern hemisphere is tilted away from the sun, and experiences winter. This combination of the Earth being closest to the sun and the northern hemisphere being tilted away from the sun leads to colder temperatures in the northern hemisphere during perihelion.
It's important to note that the effect of the Earth's elliptical orbit on temperatures is actually quite small and it's only one of many factors that contribute to seasonal weather patterns. The axial tilt of the earth, the rotation of the earth, global winds and ocean currents, continental positions, and even greenhouse gases are all factors that contribute to the temperature differences between the seasons.
It's also worth mentioning that the difference of distance between aphelion and perihelion is small, 147.1 millions KM ( 91.4 millions miles ) at aphelion, and at perihelion is 147.1 - 1.5 = 145.6 millions KM (90.8 millions miles) which is less than 1% variation . And this small variation will not have big effect on temperature.
In summary, the northern hemisphere experiences colder temperatures during perihelion due to the combination of the Earth being closest to the sun and the northern hemisphere being tilted away from the sun. However, the difference between perihelion and aphelion is relatively small and there are many other factors that contribute to seasonal weather patterns.