I20 thru Texas in December

I20 is a very busy highway and chances of ice are there but very slim. Usually ice and snow are forecast a day or 2 in advance and you can plan around meeting up with the weather.

You are better off on I10 from the Louisiana line to about Junction Texas as you are further south. IMO

Most likely, it will be chilly to cold and clear, but watch the weather forcast for a cold front coming down because those can bring a little sleet once in awhile. I 10 is the same when you get out to Sonora TX and west from there. Usually somewhere between Ft. Stockton and Van Horn. But you just have to watch for cold fronts coming down.

It is Texas. The temps can be anywhere from 0 to 90 degrees. Rarely does any frozen precipitation last more than a day, but there are exceptions. Even if there is frozen precipitation they are pretty good about sanding the bridges and keeping the interstate open.

I travel I20 from La to Yuma for last 8 years (around 1st Dec to 12th Dec) and yet to have a problem. JMO

Winter storms along I-20 in December are relatively rare. But it happens. But the same is true for I-10, especially after you get west of San Antonio.
Best bet is to watch the weather forecast for several days ahead and plan your travel accordingly. The good thing is that any ice/snow that may occur rarely lasts more than 2 days on the roadways. The odds of it being 65 degrees is greater than it being 25 degrees.

Let me ask the same question about I10.

Is bad weather less likely along this route in time period indicated?

Thanks

Depending on factors you could see ice storms in that time period. There were 2 last year IIRC one really bad. Willie Nelsons bus went off road and 3 band members were hospitalized. Willie not onboard.
In lat Nov. early Dec we were delayed 3 days waiting for an Ice storm to pass.