The Russian River Valley and Sonoma Coast are known for producing elegant Pinot Noirs. These are the cooler regions of Sonoma County, where the nearby ocean and coastal fog heavily influence the climate. From May through November, this coastal fog sweeps through this area regularly, over both our Hallberg Ranch and Pinot Hill vineyards, at the same time of year our Pinot grapes are growing and ripening.

It starts as the Hawaii Pacific High, a system of high-pressure winds that push moisture and ocean currents from the Hawaiian Islands towards California. As the winds blow over the ocean a sea mist develops.  Once this mist reaches the coast, the cold ocean air hits the warm air on the coast and forms fog, better known as the marine layer.

There are two main areas along the Sonoma coast where the marine layer moves inland: at the mouth of the Russian River and at Bodega Bay. The marine layer pushes inland along the breaks in the coastal mountain range, taking the path of least resistance. In pushing inland, it causes warmer air to rise, creating a vacuum that brings in more fog and a cool breeze in the afternoons.

When planting our Pinot Noir vineyards, we looked for areas that experience a large difference in daytime and nighttime temperatures, called the diurnal range. The Russian River Valley and many areas of the Sonoma Coast have a 30°+ F diurnal range making it the perfect location to plant, grow, and harvest Pinot Noir. Our vineyards are perfectly situated just a couple miles inland and are covered in a blanket of this cool fog from evening until late in the morning. The marine layer brings cool nighttime temperatures around 50-55 degrees.

Here’s a day in the life of our vines, a pattern that repeats almost every day throughout our growing season:

  • Morning sun burns off the fog and warm sunny afternoons give the vines energy to continue to ripen.
  • At Hallberg Ranch, the warm afternoon brings ripe flavors of rich, fresh fruit and notes of strawberry. Pinot Hill lies in a much cooler region of Sonoma that is submerged in fog almost all day, resulting in a lighter, more delicate bodied wine with tart fruit flavors, such as cranberry.
  • Ripening stops during the cool nights allowing the grapes to retain their acids. This acidity creates wines that are delicate and balanced.

So the next time you see a summer fog, give it its due! That’s what makes our vineyards such a perfect place to cultivate Pinot Noir, and makes the beautiful wine in your glass possible.

Fog over Hallberg Ranch vineyard.