A skeptical argument, from this site, argues that Shepherds would not have been out in the fields with the sheep in late December. The argument runs like this:
Luke 2:8 states that when Jesus was born, shepherds were keeping watch over their flocks in the fields. According to the Talmud, flocks were put out to the pasture in March and returned to pens in early November. That would make Jesus birth sometime during late Spring, Summer, or early Fall. During late December, the flocks would have been penned up and would not require 24 hour monitoring by the shepherds
For those believing in a December 25th date for Jesus birth, would the main argument be that the sheep were being brought out so as to get an early start in the morning for temple sacrifices? Or, could there be exceptions for the Talmudic statement?
The skeptical article doesn't mention where in the Talmudic their statement comes from. I have not found it. However, in the Mishnah (Baba K, vii.7) found here, it states:
One may not raise small domesticated animals, i.e., sheep and goats, in settled areas of Eretz Yisrael, as they graze on people’s crops.
The Shepherds could have been raising sheep on their own land that they were working on. Perhaps their flocks were destined for temple sacrifices?
Bethlehem was an area for growing grapes. Perhaps sheep could have also been brought out in December to fertilize what was growing in the fields - such as grape vines which might also include lower leaf/branch pruning of those vines growing in the fields?
Note, this is a legitimate question for Christianity because of the historical implications impacting the tradition of celebrating Jesus' birth on December 25th. It also impacts the integrity of the various oral traditions related to the church fathers.
That is to say, is there any reason to not believe that the December 25th date is grounded in the oral tradition of Mary, the mother of Jesus, sharing the date of his conception and birth with the various members of the first century faith community?
The micro-climate in Bethlehem was likely similar to weather in California. Many ranchers leave their sheep outside in December. One might argue that the Talmud was not arguing a universal principle on this point. Being out in the cold was an occupational hazard for shepherds. In Genesis 31:34 Jacob is recorded as lamenting his shepherding job, "This was my situation. The heat consumed me in the daytime and cold at night, sleep fled from my eyes."
Here is the average temperature for Bethlehem:
The first month of the winter, December, is still a mild month in Bethlehem, West Bank, with temperature in the range of an average low of 7°C (44.6°F) and an average high of 14°C (57.2°F). In December, the average high-temperature drops, from a pleasant 20°C (68°F) in November, to a mild 14°C (57.2°F). See here.
According to Emeritus Professor Epstein, of Animal Breeding at the Hebrew University of Jerusalem, the most common sheep in Israel are the Awassi breed of sheep. They are often left in the open fields even during the evenings. The only exception would be when the temperatures in high altitudes are very low with snow on the mountains. See this article by Epstein.
The article also states:
Bedouin and fellahin shepherds know nothing of tent or house but live entirely in the open together with the flocks under their care. They are working 365 days a year, from 13 to 16 hours a day. Their work includes shepherding, watching at night…In Iraq, the principal lambing season of Awassi ewes is in November, and in Lebanon, the Syrian Arab Republic and Israel in December-January…