Christmas Markets

Yes, I would wear jeans, but I wear them all year round anyway. Check average temps and weather online for those cities. It may be cold, it may snow, it may rain. Shoes or boots with thick soles will keep your feet warmest. Lots of people recommend layers, but if you are going in and out of buses, museums, etc. it is easier to just take off your coat. Long underwear might be a good idea to take, but sometimes it just isn't cold enough for that.

I wouldn't wear jeans unless you plan to try to blend in with the vast majority of the other people at these places, who overwhelmingly will be clad in jeans.
Water resistant jackets are always a good idea; especially in late fall and winter.

We travelled in this area in early December a couple years ago. Waterproof/wind resistant shell was great with layers under. Thin long underwear was useful, especially if you plan to be out walking after dark. Which we did a lot of since it was dark by 5 and there were lots of pre Christmas festivities going on. The long underwear can double as sleep wear if you happen to have a cool room. Also may depend on what climate you are used to. But there was some rain and light snow for us.

If you are going to the Christmas markets and standing around at night, long thermals under trousers would be useful. I wear a thermal thin polo neck under a shirt or fleece and a wind and waterproof jacket.

Good thick soled footwear is essential. Jeans are OK, but they can take ages to dry if they get wet.

The first time it snowed, my outer clothes got pretty wet - it wasn't very cold so the snow on me melted pretty fast even though it stuck on the ground. As a consequence, I was quite cold. After that, when it snowed, I put my trusty rain poncho over me (and my day pack) and stayed warm and dry. You may want to wait and buy hat and scarf at a market - great souvenirs.

Thanks all...thermals are a great idea that I didn't think of. Buying hat and gloves there is also a great idea, practical and great souvenir that I can use every winter in upstate New York!!

A nice merino wool base layer (Smartwool, Icebreaker) will be welcome. I wear them with jeans or hiking pants in the winter.

If you're from upstate New York you're probably used to harsher winter weather than we have here, although it can be wet (be prepared for rain as much as snow, and the rain is worse). Water proofed stuff doesn't hurt. Shoes that don't let the water in are super important.

Really though your winter clothes won't be much different from what you wear at home in the winter - unless you're going snowshoeing or something. Visiting the markets means you'll be outside in the cold for longer than you're used to, but in my experience a good hat plus gluhwein pretty much keeps you just fine.

Lol. Thanks Sarah!!