We are gearing up for harvest after a hot and dry summer in Oregon's Willamette Valley. A question we are asked frequently is, "How is the harvest looking so far?" Here are three possible predictions:
1) Growth Acceleration: Heat provides grapes what they need to develop. We measure this in Growing Degree Days (GDD). According to Oregon expert Gregory Jones of Linfield College, "Wine regions in Idaho, Washington and Oregon are now running 100-300 GDD units above normal, or two to three weeks ahead of average." We are 12% over the historic average for 1981-2010. As a result, we can expect a relatively early harvest, which we will predict will begin at our vineyards Sept 17-24.
2) Dry: Obviously, precipitation has been lower than normal on the west coast. In areas like the Willamette Valley where irrigation is uncommon, it means that we worry about the long-term water table impact, but short-term concerns are kept at bay since our generally mild climate and fertile soils usually keep things healthy even with a bit less water than normal.
3) Wine Profile: While we are above the 30 year average for GDD, we are still under recent warm vintages such as 2015. This means that wines could be robust in flavor development and alcohol, but still balanced in acidity. The recent cooling of weather encourages the probability of this.
Our primary task over the next three weeks will be to determine when harvest should begin, based on sugar levels, acidity, flavor development, and tannin predictors (skin, seed, and stem development).