Hello we will be driving from Narita to hakuba the day after Christmas in 2018. Any advice on the traffic conditions since its holiday season and any road safety conditions we need to be aware of?
During winter roads may be snowy or icy, so it is important to rent a vehicle that has snow tires and four wheel drive. If you aren’t used to driving in such conditions, read up about them in advance of your trip. The Tokyo area and highways shouldn’t be icy, but as you reach Hakuba there may be some adverse conditions.
The roads may also be very busy, especially if you’re travelling at the end of the year. Give yourself plenty of time to reach your destination (plan for up to 1.5x to 2x your estimated travel time).
I hope that helps answer your question. Let me know if I can help with anything else.