That shot has to be in Inglewood, CA. Take it from me, "It Never Rains In Southern California" At least not from April through September. First flight of the FJ-1 was on 11 Sep 1946 and deliveries began in October 1947. So, the summer of 1947 would be the likely time period.
Note that all of the F-82's had the outer wings painted with zinc chromate. I understand that all P-51's had their wings puttied with filler, sanded smooth and even the "natural aluminum" ones had the wings painted with silver lacquer. So presumably even the day fighter F-82's also had the wings painted the same way.