Harvest 2017 is far from done and has already proven itself memorable. Temperatures in the valley soared into the triple digits in late August, and parked in the high 90’s for almost a full week. Many locations up valley registered 109F on the two hottest days of the relentless heat spike. Temperatures briefly cooled into the 80’s before topping 100F again the 2nd week of September. The intense, prolonged heat initially seemed to super charge harvest - thin skinned, early-ripening varietals were ripening quickly and threatening to be damaged by the extreme temperatures. Once the early picks were in, however, it became clear that the heat had impacted later-ripening varietals in far more than visible ways. The word from all parts of the valley was that winemakers and vineyard managers were seeing a complete stall in sugar accumulation in the grapes. The heat seemed to have interrupted the vine’s ability to push the sugar load into the grapes. During a month which usually contributes to slow, even ripening in the vineyard, there were little to no changes in the ripeness of the grapes for roughly 20 days between Labor Day and the last week of September. It had a lot of industry folk scratching their heads.
October has broken with a long-ranging forecast that looks dry and mild - and what ought to be perfect ripening weather. Cabernet vineyards are beginning to adopt a more regular pattern of sugar accumulation, and the peculiar “pause” seen in harvest in September seems to be behind us. There are still plenty of tons left to harvest in Napa Valley, and it’s shaping up to be a spectacular vintage.