Lake County Climate
Lake County’s winegrape regions are the beneficiaries of ideal climate conditions that complement the pure air, elevated locales, and rich, varied soils.
Clear Lake, the valley floors, the surrounding mountain ranges, and Lake County’s proximity to the Pacific Ocean are factors in the microclimates found in the region’s AVAs – High Valley, Kelsey Bench, Guenoc Valley, Big Valley, Red Hills, and proposed AVAs for Upper Lake Valley and Long Valley.
Most of Lake County experiences a mix of bright sunlight bringing warm days and afternoon breezes that bring cooling that often results in 50-degree diurnal cycles.
Elevation along with the cooling effects of Clear Lake create a natural and perpetual “wind machine.” During July and August, daily temperature swings of 50 degrees are not uncommon. This intense cooling effect promotes good acidity, improved tannic structure, darker color, and more concentrated fruit character.
Lake County’s wine grapes enjoy high levels of UV light due to climate and clean air. UV levels can reach up to 10 percent more than regions in neighboring sea level valleys. This UV intensity triggers thicker winegrape skins, greater tannins, and intense wines with high phenolic content.
With vineyards starting at 1,370 feet and reaching up to 2,600 feet above sea level, Lake County grapes are grown in mountain climate conditions. Upper level airflows from the Pacific Ocean combine with local convections to moderate daytime highs.
Low relative humidity and varied topography permit quick radiative cooling of ridgetop vineyards in the late afternoon and evenings. Both factors allow for good acid retention during ripening.
The Mayacamas range and the mountains of the Mendocino National Forest which impart a strong influence on the local climate. Summer’s heat loses its grip in September when temperatures swing dramatically from morning chill to afternoon warmth. The cool nights preserve the acidity of the grapes and slow the ripening process, enhancing the flavor and complexity of the wine.
Cold winters and dry summer conditions throughout the regions are important factors in Lake County’s reduced pesticide and other application rates, one of the lowest in California.