This article was written by UC Davis ARE PhD students Sean Kiely and Kelly Wu It is the fourth in a series of excellent articles written by students in my ARE 231 class this fall.

California is lauded for its world-class wine,  but it wasn't always that way.  Believe it or not, California wine was once believed to be of inferior quality.  French wines, particularly Bordeaux and Burgundy were indisputably viewed as the crème de la crème in the wine world.  That all changed at the Paris Wine Tasting of 1976.  In a blind tasting between ten French and California whites and reds, two Napa Valley wines, a chardonnay and a cabernet sauvignon, wrested the crown from the French wines. After the "Judgment of Paris" California wines were never viewed the same as vintners were encouraged to continue to pursue quality wines throughout California.*  

The top 3 wine producing countries by volume are Italy, France, and Spain. The United States has consistently ranked fourth and Argentina fifth. Other high-volume producers include China, Australia, Chile, Germany, and South Africa. 

California accounts for 85% of U.S. production, but what makes California so special?  West Coast elitism aside, California's central and northern regions have a climate uniquely suitable for wine grape production, with rainfall during the winter and warm dry days in the summer. Cooling winds and fog from the Pacific Ocean and the San Francisco Bay keep moisture in the air, preventing grapes from drying out in the sun, especially in the Napa Valley (our usurper to the throne).

Outside the Mediterranean Basin, these Mediterranean climates are only found in California, central Chile, southwestern South Africa, and southern and southwestern Australia. They account for only 2% of the Earth's land surface. Soil is another major component in producing quality grapes.  The North Coast wine districts contain more than 100 distinct soil types, providing an ideal environment for a variety of grapes.

California wine grape production is occurs primarily in the North Coast, Central Coast and San Joaquin Valley.  Fresno and San Joaquin counties produce the greatest volume of wine grapes while higher quality growing districts such as Napa and Sonoma account for a relatively small percentage of total wine grape production. 

However, wine grapes from Napa and Sonoma counties command a much higher price per ton than other regions in California. The Napa/Sonoma price premium has increased in recent years.  In 1990, Napa County wine grapes sold for 8 times the price of Fresno County wine grapes. By 2018, Napa wine grapes were 15 times the price of their Fresno counterparts. 
 

In 2019, the weighted average price of Cabernet Sauvignon in the South San Joaquin region was only $346/ton while the average price in Napa county was $7943/ton, significantly higher than other wine grape varieties even within Napa and Sonoma. The high average for Cabernet Sauvignon in Napa conceals the wide range of prices; Napa reported to NASS prices ranging from $100 to $50,000 per ton depending on the Brix Index.  Wine grape prices in the San Joaquin Valley are typically lower than other regions as these wine grapes are typically shipped in bulk and used for blending and extending.  

The leading wine grape varieties by volume crushed in California in 2019 were Chardonnay (15.6%), Cabernet Sauvignon (14.1%), and Zinfandel (8.4%). These varieties also receive some of the highest prices per ton. Producers grow more of the high-value varieties. 

In recent years, wildfires have become more prevalent, threatening the wine industry, particularly in the high value regions. Some growers believe that more than half of this year’s harvest have been lost in their vineyards due to fire, as well as grapes tainted by smoke. The wildfires have also directly affected workers within the wine industry as their houses have been destroyed. These workers have been driven away from areas like Napa and Sonoma. The impact of the wildfires, along with immigration sweeps and the COVID-19 pandemic have created worker shortages which may leave many vineyards with grapes left on the vine.

The rising challenges from extreme weather events and increasing labor costs in California add greater uncertainties to the future growth of the domestic wine industry. Washington and Oregon have been increasing wine grape production and, excluding California, hold a considerable share of wine grape volume. Who knows, maybe even New Jersey could become the next California of wine.

Two of the figures in this article come from our California Crops data app. We pulled the pie chart directly from the NASS Grape Crush Report. The remaining two figures can be replicated using the R code at this link:  grapes.R

• *For an interesting look at inconsistencies in wine judging, check out  this podcast episode by Choiceology.