(Decanter) - Harvest is well underway in Napa Valley, California, but three days back in early September may prove the defining moment for the vintage, when temperatures up to forty-five degrees Celsius scorched the fragile young grapes.

‘I can’t remember a hotter weekend in September, and I’ve lived in Northern California my entire life,’ said Rob Davis, winemaker at Jordan Winery in Alexander Valley, Sonoma County.

The heatwave was the final event in a growing season defined by extreme, erratic climatic conditions. Winter saw heavy rainfall, while June met with an unexpected hail storm. But is the California 2017 vintage cooked?