We are in southern Oregon and head south and return during any time of the year but we watch the weather during the winter months. We have overnighted at rest areas or RV parks to wait out a couple of days. Most often the highways are not closed more than a day but we wait until chain restrictions are lifted. So safe condition depends on what weather and highway conditions make you comfortable.
Bob, Sandi & Marmaduke the Big Pug
SW OREGON 2004 Journey 39K, 330 Cat
If towing: a 2006 Mini Cooper or 1995 Wrangler