As July headed into August, records for high temperatures were set throughout the Pacific Northwest, but for a number of growers, the slow start to this season still has the 2022 vintage on a trajectory not seen in recent years.
Some areas are faring better than others, however, according to acclaimed climate researcher Gregory V. Jones.
“Wine regions in western Oregon are now running 6 days ahead to 6 days behind, while eastern Oregon and Washington, along with the Snake River Valley are 8-12 days behind the normal accumulation by the end of July,” Jones wrote in his Weather and Climate Summary and Forecast for August 2022.
Looking forward, though, the harvest on the horizon appears as if it will be orchestrated under temperatures warmer than the historical average — and dry conditions also will continue.
“Heading into the homestretch for harvest, ASO is forecast for warmer than average conditions over the west and much of the country,” Jones wrote in a reference to crush time for winemakers — August-September-October (ASO). “No clear indication on precipitation yet, likely near normal in the western U.S.”
The 2022 harvest marks the second vintage for Jones as CEO for his family’s historic Abacela Winery and Fault Line Vineyards in Roseburg, Ore.
“For the first seven months of the year, the western U.S. continues to see a slightly cool year north of California,” Jones wrote in his report. “The coolest conditions year-to-date have been seen in the inland PNW with eastern Washington, eastern Oregon, the Snake River Valley, and most of Idaho, seeing 2-6 degrees below average for the year.”
Heat blast in late July boosts GDD
August looks more august in terms of ramping up heat units, which are measured in growing degree days. Those figures are not all-telling, however, because grape vines will begin to shut down when temperatures reach 95 degrees Fahrenheit. The ideal temperatures for vine development and grape ripening range from 77 to 90 F.
“A warm July occurred over most of the west, with most areas 2-6°F above average while coastal zones were closer to average. Very muggy conditions along with a heat wave made the end of July miserable for many,” Jones wrote. “From northern California through most areas in the PNW, GDDs have recovered slightly but are still close to average or below what is normal for this time of year (50-300 GDD).”
At the weather station he charts in the Walla Walla Valley town of Milton-Freewater, Ore., there were 1,498 growing degree days through July 31 — fewer than the historically cool and problematic vintage of 2010 when it was 1,516 to start August. The recent 30-year average is 1,875. On the Washington side of the Walla Walla Valley in College Place, the GDD to start August were 1,450. The recent average is 1,718, and in 2017 there were 1,672 GDD.
In McMinnville — the heart of the Willamette Valley and home to the International Pinot Noir Celebration where attendees sweltered last weekend — the growing season is essentially on par with the recent 30-year average. The growing degree days stood at 1,112 for 2022 vs. 1,078 of the average. On Aug. 1 of 2010, there were just 882 GDD.
In Southern Oregon, where the drought has deepened, there are no thoughts of 2010. Roseburg began August with 1,457 growing degree days for 2022, beyond the 1,278 of 2010 yet slightly behind the recent 30-year average of 1,571. Medford stood at 1,716 growing degree days for 2022, compared with 1,470 GDD of 2010 and slightly ahead of the recent 30-year average of 1,691.
Washington State University’s AgWeatherNet logs growing degree days via its 177 stations across the state as well as in parts of Oregon and Idaho.
Through July 31, there were 1,623 growing degree days recorded at the East Mattawa Station on the Wahluke Slope. A year ago, it charted 2,221 GDD. The six-year average is 1,963. During the 2017 vintage, it stood at 1,805 when August began.
At the Benton City station near Red Mountain, there were 1,717 GDD recorded. A year ago, it read 2,357 GDD. The six-year average is 2,085. During the 2017 vintage, it stood at 1,973 when August began.
On Snipes Mountain in the Yakima Valley, there were 1,616 GDD registered. The six-year average was not available. During the 2017 vintage, August began with 1,860.
At the Alderdale station in Klickitat County’s Horse Heaven Hills, it measured 1,513 GDD. The six-year average was 1,829. During the 2017 vintage, it stood at 1,824 when August began.
Along the Columbia Gorge, Husum notched 1,000 GDD. The six-year average was 1,303. During the 2017 vintage, it stood at 1,262 when August began. Remarkably, the Woodinville station for WSU was nearly the same as Husum — 1,003 GDD. The recent average is 1,030, and in 2017 there were 1,000 heat units recorded.
In the Lewis-Clark Valley, an AVA that includes Idaho and Washington, Umiker Vineyard – the estate planting for Clearwater Canyon Cellars in Lewiston, Idaho — recorded 1,610 GDD through July 31. At the same stage last year, there were 2,274 GDD.
On the Idaho side of the Snake River Valley, SCORIA Vineyards – an estate site for Koenig Vineyards near Caldwell — the Nederends reportedly received 1,186 GDDs, well off the recent average of 1,700.
Viticulture research technician Brad Estergaard compiles data for the British Columbia Grape Growers Association. This week, he provided updated growing degree days through July. The station for Osoyoos — the Okanagan Valley resort town that shares the namesake lake with Oroville, Wash. — recorded 801 GDD when converted to Fahrenheit. That figure is not far behind the 819 GDD of the 2015 vintage that ended at 3,175 GDD but well off of the 929 of a year ago in a season that finished at 3,164. On the Naramata Bench, there were also 801 GDD. Last year, the 900 of July grew to 3,045 by Oct. 31.
However, the weather station positioned on the Golden Mile Bench leads the Okanagan Valley recording sites Estergaard charts with 844 GDD, well behind the 932 from a year ago at sunrise on Aug. 1. The 2021 vintage finished up at 3,222 GDD – the most since the 3,276 total from the 2015 vintage. Interestingly, that GDD to start August in 2015 was 832 — 12 behind the current vintage.
Drought conditions persist for much of Northwest
Unfortunately for irrigators, drought conditions have deepened for Southern Oregon and farther south.
“Year-to-date precipitation amounts remain substantially below average for most areas of the western U.S., but especially from northern Oregon, into Washington, and Idaho where wetter conditions have been observed,” Jones reported.
To the south, the drought conditions are historically worse.
“Precipitation year-to-date remains substantially below average for nearly all of California and Nevada with most areas seeing 40% or less for the year and with many regions dropping to 10% or less,” Jones reported.
On track toward third straight La Niña winter
The El Niño-Southern Oscillation is the influence of the water temperatures in the central and eastern tropical portions of the Pacific Ocean that determine many of the weather systems that travel across the United States. When the sea surface temperatures are warmer than average, they result in El Niño. If the Pacific Ocean SSTs are in the average range, then the ENSO is in a neutral phase. Cooler than average, that’s La Niña.
The vintage of 2022 has fallen under the path and classification of La Niña — a cool-to-average summer.
Jones shared the forecast from the Climate Prediction Center, pointing out “the outlook calling for a moderate-to-weak La Niña to continue until at least Sep-Nov 2022. The CPC model-based outlook forecasts that the probability of La Niña continuing through fall is now 68% and into early winter at 70%, but that ENSO-neutral will likely become the most likely category early in 2023.
“If this continues, this will be one of the few times that three winters in a row will be in a La Niña pattern,” Jones added.
That portends another wet and cool winter for much of the Pacific Northwest. For those in the Columbia Valley who weathered the recent record of 11 straight 100-degree days, that doesn’t sound so bad.