Because perihelion coincides with the Southern Hemisphere's summer, their summers can technically be slightly warmer than Northern Hemisphere summers, though ocean distribution usually tempers this effect.
The gravitational pull from giants like Jupiter and Saturn can subtly alter Earth’s orbital path over long periods. How Perihelion Affects the Earth during which month is the earth closest to the sun link
According to Kepler’s Second Law of Planetary Motion, planets move faster when they are closer to the sun. This means Earth is traveling at its maximum orbital speed in January, which is why winter in the Northern Hemisphere is about five days shorter than summer. during which month is the earth closest to the sun link
You might notice that perihelion doesn't land on the exact same day every year. This is due to the complexities of orbital mechanics: during which month is the earth closest to the sun link