I'm planning a road trip from Colorado to Smith Rock from May 11-25th. We were planning to climb at the City of Rocks on the way to Smith, and the Uinta Mts on the way back, but I just read that the Mirror Lake Scenic Byway is usually closed until Memorial Day, so I guess we are SOL. Are conditions likely to be good at American Fork in late May?

Sounds like a great trip. You heard right about the Uintas. With all the snow we got this year I highly doubt the road will be open, and if it is you will be climbing in the snow. I was just at AF this morning, it was good but crowded because only the South facing crags are dry. The North facing crags still have some snow on them, but they might be ready by mid-May.

The Uintas in May would be exceedingly cold and painful anyway. It's perfect up there starting around July - Sept, when it's really hot in SLC.

Since you're asking about AF, I assume you're looking to sport climb, in which case AF would probably be your best bet. If you climb trad routes at all, you may want to consider climbing in LCC as well. Lots of great trad climbing up there, definitely worth checking out. If not, then AF would work well for you. I'm not very helpful with conditions down there, since I don't climb in AF very often, but the south facing stuff would definitely be dry and warm, so you'll at least be able to climb that.

AF is already climbable on the sunny side. The shady crags will take a while to melt out this year. Timpanogos Cave rangers have encountered drifts as high as 15' on the trail up to the cave.