Images from the WestWide Drought Tracker and the Western Region Climate Center backed up what folks living in Pacific Northwest wine country suspected — the month of May was warmer and drier than “normal” — whatever that is anymore.
That combination sparked the 2023 vintage to take off after a slow start to the growing season, Greg Jones, the internationally acclaimed climate researcher and Abacela Winery CEO, wrote in his monthly report to the Northwest wine industry. He cited weather data collected at four stations throughout Oregon wine country — the Willamette Valley, Walla Walla Valley, Umpqua Valley and Rogue Valley.
“Growing degree-day amounts for four locations that I have tracked for many years in wine regions in Oregon are substantially above both the 1981-2010 and 1991-2020 climate normals for the March to May period,” Jones noted.
McMinnville, Red Mountain heat units take off in May
By the end of May, the McMinnville recording station Jones monitors accrued 398 GDD. During the record hot vintage of 2015, it stood at 362. During the cool vintage of 2010, it was 212.
In Roseburg, at the Jones family’s Fault Line Vineyards planting for Abacela, there were 532 GDD to start June. Eight years ago, it read 507. In 2010, there were just 250 GDD. In the Rogue Valley city of Medford, this year is ahead of 2015 with 603 GDD vs 549.
However, in the Walla Walla Valley town of Milton-Freewater, Ore., the current vintage stood at a more moderate 534 GDD. In 2015, there were already 574 GDD. The cool and slow vintages of 2010 mustered only 288 GDD to start June 1.
Washington State University’s AgWeatherNet logs growing degree days via its 177 stations across the state as well as parts of Oregon and Idaho.
Through May 31, there were 610 growing degree days recorded at the East Mattawa Station on the Wahluke Slope. A year ago, it charted 494 GDD. During the 2015 vintage, it stood at 586 when June began.
At the East Benton City station near Red Mountain, there were 665 GDD recorded. A year ago, it read 543 GDD. In 2015, there were 654 GDD.
Through May of this year, Snipes Mountain station in the Yakima Valley collected 620 GDD. A year ago, the accumulation stood at 495 GDD. During the blistering 2015 season, it was 635.
At the East Paterson station in the Horse Heaven Hills, that station measured 597 GDD. In 2022, it read 495.
Along the Columbia Gorge, Husum notched 382 GDD. A year ago, it stood at 280. The Pullman school’s station in Woodinville collected 373 GDD, compared with 247 GDD last year. Back in 2015, it received 317.
Last year, a number of vineyards in Idaho’s Snake River Valley became integrated into AgWeatherNet. Canyon County northwest of Boise includes historic Sawtooth Vineyard, which achieved 493 GDD. In 2022, there were just 302 GDD recorded. However, in 2021, there were 444 heat units by June 1.
At Rose Cottage near vaunted Fraser Vineyard, there were 494 GDD. Last year, it attained only 352. In 2021, however, there were 489 GDD.
Representing Ada County there is young Dude DeWalt at 489 GDD, well ahead of both the 2022 vintage at 331 and that of 2021 with 423.
Talk of wildfires, drought return after dry May
So far, the story of the 2023 vintage and its growing season is radically different for those to the south, Jones noted, adding, “wine regions in California and Arizona are 7-21 days behind normal accumulation amounts at this point.”
While there were no large-scale weather events that damaged buds, unlike the mid-April frost of 2022, the dry May has brought the drought back as a concerning topic for some irrigators.
“Dry conditions in May have put pressure on water availability, especially in the PNW, although most other areas are heading into the dry season in decent shape,” Jones wrote. “By state in the West, the dry May moved Washington to where nearly 55% of the state is in the lowest levels of drought and 3% in the severe category.
“Similarly, the dry May increased the area of Oregon in all drought categories to nearly 85% now, although the area of extreme drought categories (severe, extreme, and exceptional) has dropped to just under 11%. Idaho has continued to see drought coverage drop from 70% in April to just under 50% today.”
Those conditions also have heightened concerns heading into wildfire season on the cooler side of the Cascades.
El Nino likely to bring warm, dry harvest conditions
According to the forecast, it would seem that the rest of the spring and through August will be warm and dry, as a result of the El Niño-Southern Oscillation (ENSO).
“June appears headed to warmer-than-average temperatures across northern states from the PNW across to New England,” Jones wrote. “The seasonal precipitation forecast is calling for most of the western U.S. to have equal chances to see slightly above to slightly below amounts, while the northern PNW and desert Southwest are forecast to see a drier-than-average period.”
And winemakers and vineyard managers can plan for warm and dry conditions during the harvest of the 2023 vintage and beyond.
“Many of the ocean and atmosphere variables across the tropics are now consistent with developing El Niño conditions,” Jones reported. “As of mid-May, the Climate Prediction Center (CPC) is holding their forecast to an El Niño watch, which typically signals the start of the warm phase of ENSO. Most models and forecasters are pointing to El Niño persisting (greater than an 85% chance) through the forecast period into fall and early winter.”