There will be some road and campground closures starting around Nov. 15. If you're looking at a particular route, you might check the applicable USFS site.
There should be zero snow on the ground at that time of the year although every few years we might get a dusting. Once about 10 years ago there was enough snow to ski on by Halloween, but that's very rare.
The access road to the main routes to Baldy is also the road to a local ski area, so even if there were snow, the road would most likely be open.
If you're thinking of the more challenging northern route to Baldy via the Blue Ridge Road, definitely check the route's status beforehand. However, even if the Blue Ridge Road is closed, the northern route is still accessible via the 2mi Acorn Trail which starts right in Wrightwood.
Maybe you're already seen it, but the
San Gabriel Mountains Disscussion Forum generally has pretty good info on Baldy.
If it's San Jacinto Peak that you're after, then the tram is normally open (barring the unforseen earthquake or something of that nature) late Oct/early Nov. If you want the real challenge, Cactus to Clouds (10,000+ gain), you're coming at the right time of year. C2C is probably one of the toughest hikes in S Cal if not the toughest. From the desert floor at Palm Springs to the top of the peak.
The San Gorgonio Wilderness is where the majority of the peaks above 10,000' are located, including San Gorgonio Mountain (11,502'), the highest point in S Cal. I love Baldy, but that's a far more prosaic hike (in my opinion) than San Gorgonio Mountain. The South Fork - Dry Lake - Dollar Lake loop (22 miles?) is a personal favorite. There's also a more specific forum for the
San Gorgonio Backcountry Board.
Hope that helps,
HJ