Carl Sandburg suggests this song dates back to the 1870s.
Wendell Hall [n°1 US as It Ain't Gonna Rain No Mo'; also popular in UK; Hall codified what already existed, just added a few original verses and credited himself]
Ernest Hare & Billy Jones [idem]
Billy Murray & Ed Smalle [idem]
DeFord Bailey [as Ain't Gonna Rain No More]
Savoy Orpheans [as It Ain't Gonna Rain No Mo']
Tom Waits [live in Washington, DC]