What about December to visit Guilin

I'll be in HK in December (6-15) and I was thinking to come to GL for a feew days. I know it will be cold but it is still nice to come or too much rain? the cruise on the river it is possible at that time? And do you knwo the best Way to come from HK? I only find quite expensive flight.... by train it is possilbe?
Thanks a lot!