It was established by the Bureau of Alcohol, Tobacco and Firearms (ATF) on October 11, 1995, after the ATF received a petition from Mr. Charles A. Carpy, Chairman of the St. Helena Appellation Committee, proposing to establish a new viticultural area in Napa County to be known as "St.

"[2] The appellation covers 9,060 acres (14 sq mi) along the flat narrow land towards the northern end of the valley between the Vaca and Mayacamas Mountains.

[5] The area has a Warm-summer Mediterranean climate,[6] and is somewhat hotter than nearby wine growing regions with summer temperatures that often reach the mid 90s Fahrenheit.

In 1860, George Belden Crane planted Mission vines in St. Helena, and the vineyard produced its first wine in 1862.

[6] Charles Krug, one of the pioneers of Napa Valley winemaking, founded his winery in 1861 in the St. Helena district.