Um, which side of the wall are they painting, the US side? Immigrants don't arrive from that angle. And does Noem not realize that people are more likely to scale the wall at night when it would be far cooler, thereby defeating the intention of the black paint? It's all so effing stupid.
To be fair the black paint will make the wall temporarily a few degrees hotter but it will also cool faster at night. Immigrants crossing on winter nights will need good gloves to keep fingers warm. Or a ladder.
It's along the Mexican border. How cold does it get in December down there? 60? 50? Not really known for blizzards and arctic level chills. All in all, a waste of money and time.
Deserts can be cold at night especially with any elevation at all. Portions of the U.S. Mexico border are above 2,000 ft elevation. Painting the border wall is a waste of money since wind-blown sand will strip the paint no matter what they do.