Can't advises on I-10 or I-20 East of San Antonio, however to get to New Mexico via I-20 you will be using the 10 as well. Western terminus of I-20 is in West Texas out by Pecos where it connects with I-10.
Most times should not have any snow, but occasionally it does come our way. Even in December. I believe I-10 was closed & several people were killed on it from Van Horn to El Paso a few weeks ago due to ice & snow conditions. It was closed for a short time between Las Cruces & El Paso as well.
I-10 at times can be closed between Cruces & Wilcox due to snow. Not often in December.
Weather does what it wants, no matter what is normal. Always good to check the road conditions ahead of time or at least check the weather forecast.
Even if it does snow, the norm is it not last more than a day, maybe two.
Just in case, I'll pass on some info in case you neat a place to rest & eat:
Las Cruces Area & Southern NM Mexican Food plus camping and attractions in the area. At least try a Green Chile Cheese Burger.
VideoTaste of NM Pecans:
Stahmanns or
Salopek In Las Cruces: Hacienda RV Resort and Siesta RV Park are the easiest to get to, just of I-10 exit 140. Las Cruces KOA and Sunny Acres RV Park off I-10 exit 135. KOA on the mesa over looking the Mesilla Valley, Sunny Acres in the Valley.
Park Reviews Siesta RV has gravel roads & pads, Hacienda RV has paved roads, maybe concrete pads. Sunny Acres more into town, maybe cramped???
Leasburg Dam State Park is about 17 miles N of Las Cruces on I-25. With
Fort Selden State Mon't near by. A young Douglas Mac Arthur called the fort home while his father was post commander in the late 1880s.
Info for Tucson, a really neat town & area:
:) Clicky an old post some links may not be working anymore.
I-20 area near Odessa/Midland, TX:
An Older Post.
More misc information
TX, NM, AZ.
