The Climate of Howell Mountain Wine Country

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In 1984, the Howell Mountain Wine Region was the first microclimate in the Napa Valley to be granted AVA status. Located in the Eastern Vaca Hills overlooking the town of St Helena, the region’s climate is characterized by long, sunny days.

The AVA encompasses 14,080 acres but contains only about 600 acres of vineyards. Much of the steep region is logistically inaccessible for viticultural production. The elevation ranges between 1400 and 2200 feet above sea level. Most vineyards are grown at around 1800 feet.

These vines are rarely exposed to the fog that regularly blankets the Napa Valley Floor. Grapes are mainly grown on southwestern facing slopes and enjoy abundant sun exposure.

Despite these sunny days, daytime temperatures are generally lower than adjacent region located on the Napa Valley Floor. This is due to the higher elevation as well as a consistent breeze from the Pacific Ocean. These winds also keep humidity low and help to prevent mildew in the vineyards.

The Climate of Howell Mountain Wine Country

The combination of sun and moderating winds promote phenolic development as well as a relatively high level of acidity. The region has historically grown the red Bordeaux varietals (Cabernet Sauvignon, Merlot, Cabernet Franc, Malbec and Petite Verdot) as well as Zinfandel and Petite Sirah.