Partnachlem Gorge

That's Partnachklamm, and Gorge is redundant because Klamm means Gorge, in German. In addition to probably being an icy wonderland and treacherous for hiking, it will undoubtedly be closed. The website shows opening hours only for April through November.

Thanks for the German lesson, Lee. Mine has obviously lapsed. Think I like James' answer better. I've been there several times in December and had no problem walking it. Wouldn't really call it much of a hike. The most treacherous part was remembering to duck under some of the overhangs. Maybe somebody local will confirm that it's still possible to do in winter. That's when it's at its most beautiful.

Sorry, I've only visited the gorge in spring.

The website Lee linked shows the Klamm open year-round... just slightly shorter hours from November-April. I think the only time it's closed sporadically is during the early spring meltoff months, when there's just too much water. I guess that differs year to year. It's been a relatively warm November... But the accuweather.com forecast has some changes coming in the 15-day forecast. Have fun!