Winter and spring storms regularly flood parts of Sonoma County, turning low-lying vineyards into a patchwork of lakes and ponds. Dormant grapevines generally come through such flooding unharmed, since their roots need little oxygen or nutrients while growth is paused. This year, local winegrowers are asking what happens if the rain simply keeps coming.
The concern follows a June 11 advisory from the National Oceanic and Atmospheric Administration (NOAA) that predicted a potentially record-breaking El Niño. The climate pattern develops when ocean temperatures in the central and eastern tropical Pacific climb above normal, shaping weather worldwide. NOAA's U.S. Winter Outlook, released Oct. 15, calls for warmer-than-average temperatures and abundant rainfall in Northern California from December through February.
Gregory Jones, an atmospheric scientist and wine climatologist at Abacela winery in Oregon, said conditions tilt the odds toward a much wetter winter, with the potential for very strong events such as atmospheric rivers. "That could bring too much rain, too fast, and create flood conditions," he said.
Heavy rain can help vineyards by replenishing aquifers and refilling reservoirs, wells and ponds, but prolonged flooding carries real risks. Christopher Chen, a climate-adaptive viticulture adviser at University of California Agriculture and Natural Resources, warned that soil still flooded by spring could starve roots of oxygen, leading to failed bud break and major crop loss. He added that floods can strip soil of nitrogen and potassium, which vines need early in the season.
At Balletto Vineyards in the Russian River Valley, seasonal flooding is routine. Runoff from surrounding hills gathers in the Laguna de Santa Rosa watershed and spills onto farmland, including the Occidental Road and BCD vineyards. A rising Russian River can slow drainage from the Laguna and push water back across the floodplain. Founder John Balletto said a few days of flooding usually causes no trouble, but buds submerged after budbreak would likely fall off and cost the crop. His team is seeding cover crops, preferably in every other row to keep the ground stable, and securing loose items.
Last spring offers a cautionary example. A record-breaking heatwave in March triggered early bud break, and later wind and rain disrupted pollination. Clusters were smaller with fewer berries, contributing to one of the earliest and smallest harvests in recent memory. Chen expects temperatures to warm quickly next spring, which combined with extra soil moisture could encourage insects and powdery mildew. Treating mildew often means driving tractor-mounted sprayers, which can compact waterlogged soil. "It's either compact the soil with a tractor or wait until it dries out and hope the fungal pathogen doesn't spread," Chen said.
At Jackson Family Wines in Santa Rosa, vice president of farming Scott Welch oversees about 4,000 vineyard acres across the North Coast. Many of the company's vineyards sit on hillsides, so managing erosion and runoff is familiar work. Welch said the region typically receives 25 to 50 inches of rain each winter, and crews rely on straw wattles, cover crops and cleared drainage ditches and culverts regardless of forecasts. In mid-July he also told his team to stop refilling some reservoirs so they can capture more rainfall. "Our reservoirs are drier than normal right now. But that's because we're better prepared," he said.
How the weather will affect next year's vintage is hard to predict. If wet conditions last into spring, as they did in 2026, flowering and pollination could suffer, producing a smaller, less uniform crop. If most rain falls in December and January, well before bud break, the extra moisture could support vigorous growth and larger berries. Welch said winemakers would much rather have a wet winter than a four-year drought, noting that more leaf growth shields berries from birds and sunburn. "There is a better chance you'll end up with something spectacular," he said.
