The Welcome Swallow is metallic blue-black above, light grey below on the breast and belly, and rust on the forehead, throat and upper breast. It has a long forked tail, with a row of white spots on the individual feathers. The outer tail feathers (streamers) are slightly shorter in the female. Young Welcome Swallows are buffy white, instead of rusty, on the forehead and throat, and have shorter tail streamers.