You can expect frost in the mornings next to the river. Take a good warm sleeping bag if it's an overnighter. From now till May it could snow anytime. The canyon is deep so the sunshine can be scares at times.
Had some friends run down a couple of weeks ago guiding a Colorado College trip. (Riverrunner guides) They flipped a paddle raft in Skull, and had three swimmers end up in the room. The kayakers couldn't jump the eddie fence with a swimmer on back, so one of the gear boats, (powered by Zulu), was sitting in the eddie below. He was able to ferry across, into the room and pick em all up. (I heard the place is full up with drift wood.) This is the same crew that will be there this weekend, but without the college kids.