I was up there April 15-16, 2012. T-shirt & fleece weather and very dry on the NCT side. MRT was good to, with some mushy spots closer to the river, but it wasn't too bad at all. The prior year I was there around the same time of year and it snowed 2" and got into the 20's. Can never tell with Michigan weather.
Wish I could make it to the unofficial MI spring hang, but work & family commitments are keeping me close to home. The official spring hang seems to have fizzled out, so hope to make it to the Summer one.