I have done the southern tier in winter, once alone and another time with a lady friend from England. The winter is not severe enough that far south to put you off the ride. There could be several days of ice and snow keeping you inside somewhere. It gets well below freezing at times.
I have always done it east to west. Yes, sidewinds do come in from the north, and others from the west, but the fact is I kept detailed records of weather and wind directions, and they show that you also get nice stiff tailwinds and quarter-winds that push you. Some days there is hardly any wind at all of any concern.
In fact the wind will come at you and go from you in every direction on the compass, 360 degrees. However, sometimes quite strong and constant winds blow 24 and 7 from west to east, coming out of California and persisting for several days, unrelenting. I do not cycle against such a wall of resistance. When that happens it is time to haul it off the road, get a motel, watch TV, read books, go out to restaurants, and relax.
The last time I did the S-tier in winter I had a tarp for shelter, a closed cell foam pad for ground insulation, appropriate clothing, and a 15F Slumberjack sleeping bag. I had no problem with the cold.
This message was edited by Westinghouse on 10-20-08 @ 9:04 AM