Oh, Fran, do you not know about Houston weather?! It could be in the 80's for all we know! Actually, it is probably the only month of the year in which we can count on its being cold. The few times it has snowed enough to matter, it was in January.

If you come, maybe I can arrange access to Bolivar (in private hands). It takes a couple of hours to get to the next two down the road. Pt. Aransas (in private hands, as well - could make some contacts for you), and Matagorda (would have to be the right day to catch the ferry over - not available if the weather is bad, of course), and Half Moon Reef is in the general vicinity, practically on the highway.
Then, there's another few hours or so to get to southernmost Texas and cross over to Port Isabel. It's about six or seven hours if you were to drive straight from here to Port Isabel. I'll email you some more details.

It just dawned on me that you have to take the ferry to Pt. Aransas, too, so the weather would definitely have to be good.