Climate change could redraw California wine country maps

(CN) — Napa and Sonoma counties have defined American wine since the 19th century, but the delicate environment that helped make those world-famous regions could be threatened.

According to researchers in a study published Tuesday in Frontiers in Climate, climate change impacts could reduce the suitability of grape cultivation and wine production in California’s historic wine country this century and redraw the Golden State’s wine map.

Although researchers found California’s most famous wine regions may struggle to maintain wine production, parts of Northern California and the California coast, particularly Mendocino and Monterey counties, could become new wine powerhouses.

“Our findings reveal that the outlook for Mendocino and Monterey is uniquely promising because of a dual trend,” study co-author Yusuke Hiraga of Tohoku University in Sendai, Japan, said in a statement. “They are projected to experience both increasing climatic suitability for wine-growing and a decrease in extreme fire-weather days. This combination makes these areas stand out as comparatively favorable expansion zones, distinct from many other regions with either rising suitability alongside increased wildfire weather or declining suitability.”

In the study, Hiraga and other researchers modeled California’s current and future climate suitability for grape cultivation across nearly 400 locations in the state, primarily in the North Coast and Central Coast.

They found that suitability for grape cultivation in the state’s historic wine production regions, such as Napa, Sonoma, San Luis Obispo and Santa Barbara, is likely to decline under severe climate change conditions in a worst-case scenario.

They say that wine producers and grape growers will need to rethink how they cultivate vineyards as the climate changes.

“On the ground level, as a viticulturist, it is important to consider adaptation strategies to climate change sooner than later,” Hiraga said in an email interview.

“Shifting to a different variety is one of the most effective adaptation strategies as the climate change impacts on different varieties are totally different from each other. Another possible adaptation strategy is shifting the harvest time. This should be effective in adapting to climate change without drastic variety change or anything,” he said. “Even in the relatively hot regions such as Temecula, those adaptation strategies are expected to be still helpful.”

Wine production suitability, the researchers found, depended mostly on annual precipitation, temperatures during the growing season, temperature during the coldest month, and the vapor pressure deficit — a measure of how much more moisture the air can absorb before becoming saturated.

To perform the study, the authors mapped projections from global climate change models with a 4-kilometer-by-4-kilometer grid across the mainland United States based on two alternative carbon emission scenarios. The first scenario assumes climate change mitigation policies are gradually implemented while the second is a worst-case scenario.

The researchers modeled three periods for both scenarios: 1976-2005, the baseline; 2040-2069, midcentury; and 2070-2099, late century. Each grid square’s suitability for grape cultivation was predicted using a machine-learning algorithm.

Researchers found that conditions were better in scenarios with lower greenhouse gas emissions, suggesting that higher emissions could reduce wine quality by the end of the century. But it’s not all bad news for California oenophiles.

“Sonoma Chardonnay showed potential to be of better quality under future climate change,” Hiraga said.

The researchers also modeled the shifting weather conditions associated with wildfire risk and expected severity according to each grid square.

While the number of days with extreme wildfire conditions increased across large portions of the state, especially in the northern and high-elevation regions, these days also decreased in large parts of Mendocino and Monterey counties, the researchers found.

“While our study highlights long-term shifts in climatic and fire-weather suitability through the end of the century, it does not attempt to predict a specific timeline for when emerging areas will surpass currently established regions in wine-growing potential,” Hiraga said in the statement. “Such a precise forecast is complex, as the future of viticulture is shaped not only by climate change and wildfire weather but also by a wide array of anthropogenic factors.”

The researchers used an algorithm trained on wine ratings from professional tasters, published between 1996 and 2023 in Wine Spectator magazine, to predict future wine quality by year.

California is responsible for about 80% of the total wine production in the United States and is the fourth largest wine producer in the world, according to the Wine Institute. The United States trails only behind Spain, France and Italy in wine production.

In a similar study published in 2025, Hiraga and his team found a similar pattern for Japan’s wine map, with current wine regions like Kofu Basin, roughly two hours west of Tokyo, likely to see decline, while northern prefectures may start to become more hospitable to viticulture.