January is the first month of the year, and the first day of the month is known as New Year's Day. It is usually the coldest month of the year Northern Hemisphere and the warmest month of the year within most of the Southern Hemisphere. January is named after Janus, the god of beginnings and transitions. If you have a puppy due in January, you could name him or her with our collection of January-inspired dog names. For instance Janus is a good name for your little dog.