Outdoor onsen

Would like to know if it is acceptable to wrap a bath towel to outdoor onsen in January? Not to enter the hot spring with it of course, but to at least have a layer from the cold (even though probably not much). Thanks.

It would be awkward and inconvenient, but it does not violate any rules as long as you keep the towel out of the water. It would be awkward because normally people do not bring their large towels into the bathing area or wrap themselves in towels. It would be inconvenient because you would have to put your large towel somewhere dry while you enter the water which can be a challenge depending on the bath and weather conditions.

Most people survive walking the short distances between building and outdoor bath without the need of clothing, especially if they first warm themselves up in the indoor bath. If you get hot in the indoor bath, it can even be refreshing to take a short walk through the cold air outdoors.

You can decide on the spot.

As Uji-san said, it can be inconvenient to bring a big towel but itfs not forbidden as long as you donft bring it into the water.
Normally youfd get warm enough in the indoor pool that you donft need it. Even if there isnft an indoor onsen you can probably stand freezing temperatures for just a few secs before the bliss of rotenburo.

Enjoy your trip to Japan!

Appreciate the replies and Happy New year! Can I also ask is it ok to go right into the hotsprings if we wash up and bathe in our hotel rooms right before? We'll be staying at an onsen hotel. Thanks again!

No, you should rise yourself with water before entering the bath. Depending on the bath, you can use water from a special fountain for that purpose with a ladle, directly from the bath with a bowl or from a shower.