Would like to find out the Train/Bus from FCO Rome to Cascate del Mulino. We'll be travelling to Italy in the beginning of December, arriving 19:00.

Could water be too cold during that period?

I understand that it has limited public transport service in that region. Thus, would it be better to do a night stay in some where near the hot spring, and move on the following day?

I have been reading the previous similar posts, if driving is recommended, how will be the traffic like from FCO to Cascate del Mulino?

Hope to hear from you soon.