[villagetinker]

OP, are you responsible for the maintenance of the wall? If so, look for an area that is shaded, and borrow a hammer and chisel and chip off some of the stucco. If this is a common wall you may be able to check with a neighbor for a shaded area to get an accurate color. Other option would be to get several of the paint chip cards and hold these up to the shaded area and pick the one that is closest to the color of the wall. Then use that to get the correct paint for stucco. You will also need to get the correct knapp roller for stucco.