Ran on March 20th, which I think was just before the Spring Break for most universities. The water was low (600-700 cfs) and came up to about 1000 cfs just before our launch. The water was definitely cool but not grippingly cold.
Weather was good- warm days and a few brief thundershowers. I slept in a bivy sac (or half out of it, most nights). Saw one other boat the whole time, an outfitter raft daytripping from Sand Island to Mexican Hat. The following week, when the Spring Break crowds arrived, had hard rainfall and a bit of snow, with gusty winds.
Which is to say you'll be chancing it as far as water level and also weather. That worked out for me.