December hiking in yosemite

Even if the weather holds and snow doesn't fall and stay, the chances of getting snow increase with each passing week, and in December you will have a real good chance of either showing up to a lot of snow already on the ground, or getting it while you're out there. I wouldn't even risk it unless you are comfortable navigating without obvious trail markers. That's not one of the trails flagged for winter use.

Late spring is a better time – the creeks will have water in them, the snow will be melting instead of accumulating, and there's less likelihood of icy granite.

A better winter destination would be Badger Pass – you can snowshoe or ski to Ostrander Ski Hut, or to Glacier Point, with or without a guide.

Great advice from Lori above. Glacier Point Road out of Badger Pass in the winter has a number of great trails for skis or snowshoes from day trips to multi-day. I snowshoed to Lake Ostrander last year, which was a solid 3-day (2-night) trip for my sister and I. Navigating in the area is relatively easy thanks to the flags in the trees along the trails.

I would personally be concerned about going out in December or January and assuming I could hike out. A winter storm in Sierras could strand a hiker. For a multi-day trip, I feel much more comfortable with a couple of feet of snow on the ground and heading out with snowshoes or skis in the winter months.

there are a few areas that are lower than the snowline in and around Yosemite. Some spots around Mariposa along the North Folks of The Merced or even Hetch Hetchy which is around 5000 feet around Rancheria Falls. Other than that, your options are limited. I would try coastal areas like Point Reyes, Ventana Wilderness