Um...no. I have only been to DL in Sept.; I have only experienced a very mild sprinkle (twice) in all my trips. The longest one lasting 15 minutes. Neither one even worth breaking out an umbrella, let alone the need for a poncho. The upside to it is, the locals all run for cover or indoors during this, which means all the ride lines (that are either outdoor rides, or indoor rides with outdoor lines) get way shorter fast. IF it does start to sprinkle, make a bee-line for your favorite, normally long wait attraction and jump in line.