Yes to the first question. It may, to the second.

Shortly after we arrived at the North Rim on July 24, a thunderstorm (with pea-sized hail) passed over the area. Usually “monsoon season” in the Southwest means afternoon thunderstorms, but every now and then (like yesterday afternoon for us) it’s a longer rain event.

You’ll need to check local weather forecasts closer to the time of your trip. And don’t stand near the edge during a lightning storm.