The Bible doesn’t give a date for the “birth” of Jesus. Some claim it was in the Spring or Fall because shepherds were in the fields, but this is a misunderstanding of the Jewish winters that actually had shepherds in the fields around Jerusalem in the winter because winters in Israel are mild with light snow in the mountains.
So in the Spring and Fall, the shepherds were actually up in the mountains with their sheep instead of the fields around Jerusalem so Jesus could not have been born in those seasons. There are other indications that Jesus was born in winter. You can learn more at the following links:
WHAT JEHOVAH’S WITNESSES NEED TO KNOW ABOUT CHRISTMAS (4Jehovah.org)
ARE HOLIDAY AND BIRTHDAY CELEBRATIONS PAGAN? –A Simulated Dialogue with Cindy (a Jehovah’s Witness) and Karen (a Christian) who discuss this section of Lesson 11 in the Watchtower’s brochure, What Does God Require of Us?