Kan det vara Rabben och de 29 häxorna av Marilyn Hirsh?
Bildstilen ser ut som den artist du beskriver:
Goodreads -sidan nämns också dansen och torra kläder (från en recension):
I like the concept that witches only come out on full moons and scare the villages. But they won't come out on full moons when it rains. Therefore, if 29 men went to the witches caves when it rains, and were dry, well that would be some trick. The witches wanted to know how the men could walk between the rain drops and not get wet. So the Rabbi and the men lured the witches in the rain to dance...and you can guess the rest...a whole Wizard of OZ "I'm Melting, MELTING M-E-L-T-I-N-G"
Hittade med sökningen "trick cave witches rain picture book".