Hello how may I help you? Hello, can you find me some information? Sure thing! What is the biggest and recorded cloud of all time? Do you mean the tallest. widest, or heaviest? But I meant the widest cloud Oh, the widest. That would be a cumulous nimbus cloud in 1999. How heavy was this cloud? Do you mean heaviest pre or post rainfall? Before rainfall When it was at it's fullest size? Yes. It was 16000 tonnes.