Hi! DH and I went the exact same time last year and it wasn't very cold at all. We didn't need thermals or even big coats. We had a lot of fog the last morning but that cleared up around midday. Obviously it could be completely different this year! We've always been lucky with the winters in Paris and only had an hour of rain on our last 3 visits.
this is going to sound bizarre but i was actually hoping it would be very cold i think it will just add to the xmas atmosphere...was really cold one year we went and we loved it! we used to live in canada so are used to very extreme temps..have snow suits, thermals etc for kids. guess we can just hope for the best...would rather it be cold and dry rather than wet and warm!
We're off just before you and we're hoping it will be cold and dry too, we went in November 2010 and we had no rain, it snowed lightly for half an hour one day but that was it x