I visited about a dozen Napa vineyards yesterday and today. Seeing 20-30% shatter in vineyards that pruned early. I am guessing some recent rains caught various vineyards during flowering? Seeing less shatter with late-pruned vineyards. Also seeing more among the usual shatter-prone Cab clones (4, 6, 30) and less in 169, 685, 7, 8. One very important (and large) vineyard for a large Rutherford winery looked down 66%. Not sure what happened there. Overall, I am guessing tonnage will be down 20%+ overall this vintage, and who knows what more will need to be dropped at Veraison.
For wineries that feel they are over-extended and purchase Cab fruit by the ton, this might be good news. For growers, less so.