This past week has brought unprecedented weather conditions to Oregon, and in particular to the Willamette Valley, the heart of Oregon’s wine production. The timing was unfortunate as grape harvest was in full swing. With bunch weights averaging about 10% to 20 below average, all signs were pointing to an epic vintage of exceptional quality.

The unprecedented combination of weather events, described by meteorologists as a once in generation phenomenon, fanned over 35 major fires in the Pacific Northwest. As of September 12, more than 500,000 people have either had to evacuate or been told to prepare for possible evacuation, hundreds of homes have been destroyed and more than a dozen people are believed to have perished.

In the Willamette Valley, the smoke has created a surreal orange sky reminiscent of depictions of the Martian sky or a sci-fi dystopic, end of the world thriller. The smoke laden skies have also raised fears that this year’s wine harvest would be affected by smoke taint.

To address that concern I recently spoke with Dr. Greg Jones, the Director of the Evenstad Center for Wine Education. Dr. Jones holds the Evenstad Chair in Wine Studies, and is a professor and research climatologist in the Department of Environmental Studies at Linfield University.

JM: How unusual are the weather conditions that Oregon experienced over the last week?

GJ: The weather conditions leading up to and causing the current situation in Oregon and the western US was unprecedented and likely a once in generation event. A very large high pressure area stretching from the desert SW to Alaska brought extreme heat and very dry conditions to the western US.

The dome of high pressure pushed the jet stream into northern Canada and forced cold air southward into the Rockies and the central US. This outflow of air brought strong winds from the east toward the west coast.

These winds moved over numerous mountainous areas, warming, drying, and increasing in wind speed. The result was a dramatic drop in dew points, lowering relative humidity (to 8-20%) to desert-like conditions even to the Pacific coast.

This same event brought cold air to the Rockies with temperatures dropping 60 degrees or more in one day and significant snow to the mountains and the front range.

JM: What’s been the impact of the fires and the resulting smoke?

GJ: Prior to Labor Day, the few fires that were in Oregon were starting to be brought into control. However, with the onslaught of the strong winds and drying conditions any small fire had the potential to become large very quickly. The result was catastrophic fire developments across the state.

Smoke covered much of the western part of Oregon and continued to blanket California. Initially, most of the smoke in Oregon was at higher altitudes. As winds have calmed, which has helped the firefighting, they allowed the smoke and ash to drop to lower altitudes in the Willamette Valley and elsewhere along the western valleys of Oregon and California.

One aspect of the smoke in the air is that it has lowered daytime temperatures significantly, 5-25°F or more, from what would have been seen under clear skies. Wind flow patterns are expected to change with the potential for some fresh onshore airflow and possible rain by next Monday or Tuesday.

JM: What impact will all this smoke have on this year’s wine production?

GJ: This issue is very complex. Unfortunately, it has been reported by the media as simply a fire + smoke + grapes = smoke tainted wine. That’s simplistic. Not all smoke produces smoke impacted wines.

There are some things we know and many things we don’t know about this issue. How far the smoke travels, the smoke’s composition, the level in the air that the smoke is at, the timing during the vintage, and how long it lasts all play a role in whether any smoke impact might occur to the wines.

The additional complication is that grapes may not have any direct flavor or aroma of smoke, but through the fermentation of the grapes a chemical transformation can occur which results in an ‘ashtray’ characteristic to the wine. However, none of these results are preordained, so I urge caution in how this information is conveyed and what conclusions are reached.

The Oregon Wine Board, an industry trade association, noted that while current conditions were unprecedented, Oregon wine producers had a long history of dealing with smoke from forest fires.

The fires affecting vineyards and wineries in OR are part of much larger set of nearly 100 burns so far affecting a wide range of communities and crops. This year we have fire or smoke drift pressure covering every wine producing region in Oregon. As of September 11, fires have covered over one million acres; about twice Oregon’s annual average. Although the extent of the fires are unprecedented, Oregon winemakers have a long history of successfully mitigating wildfire smoke damage.

An informal survey of leading Oregon wine producers confirmed that notwithstanding unprecedented environmental conditions, the grape harvest was proceeding as normal and that wine producers were continuing to expect that 2020 would be an epic vintage for Willamette Valley wines.

According to Jim Bernau, President of Willamette Valley Vineyards:

While the impact on some rural families and small businesses has been devastating, Oregon vineyards and wineries remain safe. There has been a lot of smoke in the valley these past few days but is not expected to “taint” the grapes.

Ryan Harris, President of Domaine Serene, echoed those comments, noting that:

At Domaine Serene, we are extremely optimistic about the fruit quality in 2020 despite the wildfires in Oregon. The growing season has been ideal. Dry, warm and consistent with cool evenings promoting balanced fruit and great tannin ripeness, color and flavor development. We have been largely unaffected by the fires themselves but have experienced a few days of smokey conditions. The weather is changing as we speak with an on-shore breeze already starting to bring fresh/clean ocean air to the area.

Harris went on to note that concerns that smoke taint would affect this year’s grape harvest were both overblown and premature:

We are keeping a close eye on the vineyards for any effects of the smoke, but haven’t seen any signs so far and don’t expect this to have any noticeable effect on the wines. It typically takes prolonged exposure to the smoke of 7 -10 days+ to generate detectable levels in the wines and we don’t expect the smoke to be near our vineyards for more than a few days. Rain is expected on Mon/Tues which should dampen the smoke and clean up any residue in the fruit. Should we be able to detect any smoke effects through testing, we are exploring washing techniques upon grape intake to mitigate any effects.

According to Alison Sokol Blosser, CEO of Sokol Blosser Winery:

How are the fires impacting the grapes? It’s honestly too early to say. We still believe the 2020 vintage will be stellar. The small set caused by rains during bloom means very small yields and bodes well for exceptional quality. The last year we had a similar set was 1999. The last year we had fires in the region was 2018. Both produced exceptional vintages. 

Southern Oregon has been equally hard hit by the forest fires sweeping the Northwest. Kiley Evans, winemaker at 2Hawk Vineyard & Winery in the Rogue Valley noted that the smoke might actually have some benefits for wine producers by extending hang times but that the region was economically and psychologically devastated by the impact of the fires.

We have some smoke in the valley now and it is forecast to remain in place a couple days before clearing out with the onshore air flow that we typically see this time of year. The best thing about the smoke is that we have not been nearly as warm during the day as predicted and that has really slowed ripening. We should get some extended hang time and will end up with ripe, flavorful, exquisite wines. Except for the outlier fire events the vintage reminds me of 2003 with the heat, fruit intensity, and ripeness, but with better acid and riper tannins. 

Honestly though I am having a hard time putting the total destruction of so many homes and businesses in the Rogue Valley aside to consider how the fires are impacting the wine industry. The impact on Southern Oregon has been immediate and substantial from both an economic and psychological perspective. The aerial footage I’ve seen of the burn areas is downright apocalyptic. 

While the events of the past week have been unprecedented and devastating to many rural communities in Oregon, its impact to date on the Oregon wine harvest has been minimal. 2020 remains on track to be one of Oregon’s epic vintages.

(Updated September 12, 2020)



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