Quote Originally Posted by Ricanada View Post
We are planning to head as far south as possible making the best time, responsibly, so that we are able to begin using our travel trailer for our accommodations.
You do have a bit of a contradiction - trying to get south so you can start using your trailer without being too cold and trying to get California as quick as possible are really goals that work against each other. If you go south first, you're adding miles, which means you're going to take longer to get to California.

It looks like you're trying to find a middle ground between those two goals, but even that doesn't work all that well. As mentioned, you really can't predict the weather more than a few days in advance, and I-40 stays at a high enough elevation where cold temperatures are common across the entire route. I don't know what you consider to be warm enough to use your trailer, but I suspect you'd have to be going all the way down to I-10 before you could reliably expect temperatures to be above freezing overnight - and even that's far from a sure thing, as even I-10 does see winter storms from time to time. Of course, you could hit a warm stretch, where I-40 is warm enough to comfortably camp.

Just for comparison sake - as you mentioned we are in a cold stretch right now but it could easily be just as cold in January - here's what temperatures would look like if you were camping overnight today on some of your route options.

The route you mentioned:
Louisville - 23F, Little Rock - 36F, Amarillo - 37F, Flagstaff - 21F. As Dave mentioned, you'd need to get to at least Little Rock, as Memphis to Amarillo is way too far to attempt in one day. Even Little Rock to Amarillo, and then Amarillo to Flagstaff is really more than I would recommend while pulling a trailer and traveling with small children.

If you took a more direct route through St. Louis, which would make for some easier driving days, your stops/temps would be:
Terre Haute, IN - 16F, Tulsa, OK - 36F, Tucumcari NM - 37F, and the Flagstaff again - so your temperatures don't change all that much.