What can we say about when Jesus was born?
I found the following
For example the Qur'an states in 19:25: "And shake towards thyself The trunk of the palm-tree: It will let fall Fresh ripe dates upon thee"
This suggests that Jesus was born in spring/summer but it is quite feasible these ripe dates "appeared" out of season by a miracle of Allah.
Shaikh Ahmed Deedat (YouTube) argues that:
But According to the Bible as well as Qur'an Jesus Christ was not Born in December
quoting the Bible and the above ayah.
There is a discussion about this on religiousforums.com.