You folks have reminded me of three other instances:

Twice we've been turned around by rangers because there was an active fire where we were headed. We couldn't see it...but they had stationed someone at the trailhead to stop all traffic.

And once we had three hikes planned for the South Lake/North Lake area. The first one hammered us with hail from a storm that was expected to end the day before. When we hiked out two days later, the storm was still there, and clobbered us with rain just as we reached our car. We day hiked the rest of our vacation, and ran into many backpackers who told stories of hail the size of quarters pounding them. We were glad we were down below.

And finally, we once day-hiked to Chilnualna Falls near Wawona in winter. The trail was stunning...but the snow got deeper and deeper, And about 100 yards from the top of the trail, it edged along a precipice about 700 feet high. We could not see the trail, only deep snow. And we backed off because we didn't know exactly what was underneath that snow...and we didn't want to find out that there was air.