Generally, Chessington is not as badly affected as Thorpe Park is by the weather. (This is understandable as Thorpe Park has many more thrill and larger rides). I think rides such as Dragon's Fury and Vampire are affected the same as Colossus and Nemesis are for example. Usually, if it is just spitting, most if not all of the attractions will remain open. If it is torrential rain however, it is more than likely that more attractions will close for the duration of the severe weather. But then again, Chessington has Tomb Blaster, Bubbleworks etc which are indoors, therefore won't be affected by the rain. And many of the rides that are not very tall won't get affected by weather very easily. I know that in the past on my visits Ramases Revenge has experienced some difficulty operating in the rain, as did Samurai before it was moved.Hope this helps .