This report describes the impacts of climate and phenology on vintage for the Rogue Valley in Oregon in 2020. A mild and dry winter in 2019-20 was followed by a dry growing season continuing the ongoing drought concerns for Oregon and the majority of the western US. The spring was relatively cool with mild frosts into early May, then followed by wide swings between early season heat then cool, wet conditions leading up to and during flowering. The result was widespread issues with fruit set leading to generally high amounts of shatter, smaller berries and clusters for many in the region. Heat stress during the summer was moderate, leading into what looked like a decent September weatherwise until the Labor Day extreme wind event, which was followed by catastrophic fires and smoke for days. Growing degree- day totals for 2020 ended up moderately higher than the previous vintage and above the average of the last 15 years. Across sites and varieties in the region the phenological timing averaged April 16th for bud break, June 5th for bloom, August 10th for véraison, and September 22nd for harvest. Growers reported generally low disease pressure, relatively low pest pressure, little to no bird pressure until later in the picking window, and a harvest that presented very good quality fruit at moderate to substantially lower yields due to bloom to fruit set weather conditions.
Jones, Gregory V., "Vintage 2020: Rogue Valley Reference Vineyard Report" (2021). Linfield University Wine Studies Reports. Report. Submission 42.