If you're thinking of overnighting at WM etc a little forethought helps.
Last December 28th a storm closed parts of I-10 in far west Texas leaving a bunch of us in Fort Stockton, all RV parks full, most motels full. There were several dozen RV's in the WM parking lot that evening.
We were okay, and would have been just fine except we had only 2-3 gallons of fresh water and the OEM battery in our new rig wasn't up to running the furnace fan overnight in 20 degree weather.
Next time we'll be better prepared.