Another tip. -
don't plan on having any forewarning that the rain is going to hit!
When we used a stroller, I used to start covering it with the rain poncho in stroller parking once noon hit (Aug and Sep trips) as the first few trips we'd come out of an attraction to bright blue skies but in the amount of time it had taken us to wait in line and ride, the heavens had opened and everything in the stroller was SOAKED!! You'd think I would have learned the first time but it's safe to say I was a pretty slow learner and lulled by the bright blue skies.
It got to the point where my 3yo would say, 'uh oh mommy, it happened again!'