Fort Leaton, just east of Presidio, is a great place to go in the dead of winter. Just off the Rio Grande, the temperatures are generally quite comfortable and warmer than at the higher elevations in the region. From the TPWD website: " Fort Leaton State Historic Site, consisting of 23.4 acres, five of which are the site of a pioneer trading post, is located in Presidio County. The park was acquired December 8, 1967, by deed from a private owner and was opened to the public in 1978.
In 1848, Ben Leaton built a fortified adobe trading post known as Fort Leaton. He dominated border trade with the Apache and Comanche Indians before he died in 1851. In 1936, the Texas Centennial Commission placed a marker at the site."
In addition to visiting this beautiful adobe structure--which is a photographer's dream--Fort Leaton (along with the Barton Warnock Environmental Education Center) is a place you can buy backpacking and camping permits for Big Bend Ranch State Park.