There has been a 40 degree difference in temp between the bay and the central valley until the last couple days, with strong breezes. The forecast is for fairly mild temps (ie under 80 degrees) this weekend, so wind may be much lighter. But as long as there is some gradient, you'll be fine. One thing to watch, though, is that if a weather system is superimposed the flow can actually reverse. I haven't done the ditch "run" but it wouldn't be as much fun as the delta ditch "beat."

Have fun!