Is there any evidence the Magi celebrated Christ's birth on December 25th...?

It was chosen by the church much later. That does not mean that it is invalid for people to celebrate the birth of Jesus on that date.

Yes, the Church did co-opt the date. December 25th was the date of the winter solstice in the old calender (before Gregorian). Celebrating the "re-birth of the sun" became celebrating the birth of Christ (one of whose many titles has also been the Sun of Justice). Certain denominations have problems with this but what really matters is the current reason for the celebration, not what it once was.

Christ's birth, according to Christian speculation, was more likely to have been in the spring, because the shepherds were out herding their sheep. In any case, the magi (wisemen) did not come to Jesus on the night he was born. They likely came much later. I believe December 25th was just chosen by the catholic church and held to this day.

No, but in Luke chapter 1 is important information about the time of Jesus' birth. Mary was cousin to Elizabeth, who was pregnant with John (the Baptist). Shortly after Mary discovered she was pregnant (with Jesus), she visited her cousin. This happened in December.

Jesus was probably conceived in December, which suggests he was born in September. It is noteworthy that Jewish tradition dates the life of a child from its conception, not the date of its birth. Here is some information from a Jewish friend about when Jesus was born:

"If He was born at Sukkot/Feast of Tabernacles, in the Fall Feasts, as MANY worthy Biblical scholars can figure out from the scriptures, then that would have him being conceived at about the time of Hanukkah. And what does that mean for us? Wow...Ye'shua is the Light of the World. When does God believe a baby is "born" or 'comes into being?' At conception."

As for the year - well, that is also not specified but clues about John the Baptist being born in spring 7 B.C. would indicate autumn 7 B.C. for Jesus. (John was six months older than his cousin, Jesus.) That year was also a rare one that had a triple conjunction of Jupiter and Saturn, which could fit in with the account of Magi from Persia seeing a significant star. The first conjuction would be in May and they would then have plenty time to plot the next two conjunctions (in the autumn) and travel the very long distance to Jerusalem (over which the second conjunction appeared) at the time of Jesus' birth. Herod the Great told them the prophecied King would be born in Bethlehem. And by the time the third conjunction happened, it brought the Magi to Bethlehem, to the very house where Mary and the child were. This implies a bit of a time lapse between Jesus' actual birth in a stable, and being a child in a house in Bethlehem. Clearly, the stable accommodation had only been temporary! And the Bible shows that Mary and Joseph stayed local as Mary went to the temple in Jerusalem for her purification.

Interestingly, there was also a census that year, written about by 5th century historian Orosius. He said Augustus ordered a census of each province everywhere, with all men to be enrolled to show allegiance to Caesar Augustus. Josephus notes that "When all the people of the Jews gave assurance of this goodwill to Caesar, and to the king's government, these very men [the Jewish Pharisees] did not swear, being about six thousand." This census took place in 7 B.C., and was for non-Romans. Romans wouldn't need to be registered as showing allegiance to Caesar. But Joseph would need to be registered, which accounts for him taking Mary to Bethlehem where he'd been born. I'm opting for late September, 7 B.C, when the Magi pitched up and gave gifts for a King to a baby in a cattle stall. But don't forget - Jesus' conception would then have been late December!

AiH

Absolutely not---the December 25 date is the birth of Mithra, the name of a Pagan Religion of 600 BC of Babylon--used by the Roman Universal Catholic Church to show honor for their pagan god the Sol Invictus. There is nothing Christian about the date but is now imbedded by most Christians all over the world--that does not mean we honor Mithra but in fact---date being no guide--honor the birth of Jesus the Only Begotten Son of God the Father and Mary--the human mother of Jesus the Christ. We Christians do not honor Mithra in any way.

Yes. Archeologists unearthed a stone tablet from Walmart that was a rain check made out to them dated December 25th for a tickle me Elmo doll.

No it was late Sep fall harvest

Yup, the birthday of the Son God... just like sunday,