Hokkaido in january

Hello,
I m planning to spend 5 days around Hokkaido, we love natural parks, hiking, onsens, we also love seafood. My question is about the weather, and if the natural parks are available to be visited during january.
Thank you so much.

Weather
There will be much snow.

Parks are open but due to the snow it is not advised to do trekking unless you have proper equipment.

Not part of the Qn but:
For seafood Hakodate has many seafood restaurants.
At the market you can get seafood, there are small eateries by the shops where they can cook the seafood you buy on the spot (usually with a extra fee)

For onsen
Noboribetsu is the most popular

Lake Toya has some pretty good views

Daisetsuzan area like
Sounkyo

Thank you for the quick answer.
So, i guess that you recomment enjoy hoakkaido outside activities during spring, summer or autumm, better than winter? (i'm from barcelona...and now we are around 15º ;-)
If we want to do cross-country skiing, wich place do you recommend us?
Thank you again

If you're looking to hike, the summer would be much better. There is A LOT of snow in Hokkaido in the winter. It is very beautiful though, and I would certainly recommend checking out Sapporo and Hakodate (the two destinations I have winter experience with). If you do go to Hakodate the ropeway is a must for the incredible view, and if you can delay your trip to February the Snow Festival in Sapporo is something to see for sure.

I spent most of my time snowboarding in Hokkaido in the winter. I would say outside the snow festival that is the primary tourism draw in the winter, but hopefully some others can help you out better.

If for trekking then winter is not a good idea. For everything else, Hokkaido is great all your round. That said, I like it best in Autumn (Colorful) and summer (Longer daylight hours + Lavender fields)

Dipping in an onsen in winter is in an experience. Especially after a day of walking about or skiing.

Can't help with your skiing Qn.
Niseko is what I've heard but personally unexperienced.

Hokkaido is absolutely amazing in winter if you are into snow. The skiing is phenomenal and there are tons of great resorts to check out. I've been to Niseko, Rusutsu, Tomamu, Sapporo Teine and Furano to name a few and they were all great. Snowshoeing and cross country skiing are possible if you are into that. The national parks can be visited in winter, but the access becomes a problem. Which are you interested in? Some have special things to see in winter like the drift ice near Shiretoko or the Kushiro cranes.