Sonoma County has their own off shore bank, but the coffers do not contain the usual currency. Instead there is an upwelling of cold water that fills the fog bank just of the coast of Sonoma, caused by a sharp drop off in Pacific Ocean floor. The warm surface water is pushed further south by the flow of the cold deep ocean currents, creating cooling fog. At the southern part of the valley the Petaluma gap ushers in the fog each morning, while the afternoon sun chases it away. The diurnal temperature swing can be as much as 35 degrees in the summer. The cool nights and mornings give the wines a vibrant backbone of acidity and freshness while the afternoon warmth allow the grapes to fully ripen. Fog and temperature are not the only contributing factors when it comes to growing grapes in Sonoma. As an appellation on a major fault line, the San Andreas, there are many soil types. Rumour has it that there are more soil types in the Russian River Valley than there are in all of Burgundy. Add some altitude to the mix and you have a recipe for wide diversity of wines. As part […]