Am I the only person who doesn't feel the need for a poncho in the rain? It's only water, people! Especially if you have a hat with a brim all around (like a painter's cap or "bucket" hat) so your face/glasses stay more or less dry.
I've been lucky, I haven't seen rain in a Disney park in over 15 years... not a drop over 8 days in January, none during a 2-day
Disneyland trip last year, none during four days around Thanksgiving in 2003, none in any of the trips before then until at least 1989... I guess it helps not going right in the summer months, of course that's when I'd really want some rain, to cool things down!
If it rains on the next trip, I'll be sure to take pictures.