A Single Drop of Rain was the ninth episode in Season 4 of Quantum Leap, also the 62nd overall series episode. Written by Richard C. Okie as a teleplay from a story co-written by series creator Donald P. Bellisario, Okie, and Ralph Meyering, Jr., the episode, directed by Virgil W. Vogel, first aired on NBC-TV on November 20, 1991.