RAIN MUSIC
How about a collaborative set of recollections about this kind of stuff? Recent family recollections have included:

Rain on the roof of the Brunswick Heads 'Piture' Theatre during an odd double bill of the 'The Pink Panther' & 'Star Wars' - you see on summer Hols you only go to the pitures if its raining or likely to!
'Tony's' corrugated iron Empire Theatre (walls & roof) in Mullum and my earliest excursion to 'the pitures', 'Queen Elizabeth's Coronation' and I'm certain it was raining for that!!

AND, I remember going to see 'The Sound of Music' in a CI Theatre (well I guess that's what you might call it) in Nandi Fiji. It was raining again as it does on CI theatres but the kids were running sticks along the walls and as I recall there was a rather prolonged dog fight that started up during the love scene - who said traffic noise was a problem??