january is a winter month in the northern hemisphere and a summer month in the southern hemisphere. in each hemisphere, it is the seasonal equivalent of july in the other. perihelion, the point in its orbit where the earth is closest to the sun, also occurs in this month, between january 2 and january 5. january begins on the same day of the week as october in common years and on the same day of the week as april and july in leap years. january ends on the same day of the week as february and october in common years and on the same day of the week as july in leap years. january is the only month of the year that always has a "twin" - a month that both begins and ends on the same day of the week as it does. in a common year, this is october, and in a leap year, july.