The distinguishing features of the Paso Robles Willow Creek District viticultural area include a strong marine influence, an average annual precipitation of 24 to 30 inches (610–760 mm), a cool Winkler Region II growing season climate, and a mountainous landscape with elevations of 960 to 1,900 feet (290–580 m).

For example, a March 17, 2007 article entitled "Hands-On Hobby" in The San Luis Obispo Tribune discusses winemaker Charlie Poalillo and his "Willow Creek grape-growing business," and an article entitled "Paso Robles Boy Has His Wish Fulfilled Saturday" in the June 22, 2005 Paso Robles Press discusses a young Make–A–Wish Foundation recipient who is described as living on his family's Willow Creek area ranch.

Further, the "Willow Creek" name is used by some local wineries to more specifically describe the location of their vineyards in the Paso Robles viticultural area, according to wine marketing materials provided with the petition.

The northern portion of the boundary of the Paso Robles Willow Creek District follows a rugged, mountainous ridgeline and eventually descends eastward to the Salinas River floodplain.

The northern portion of the boundary follows roads, intermittent streams, and the city limits of Paso Robles as marked on the provided USGS Templeton map.

The eastern and southeastern portion of the boundary is based on the transition from the soft Monterey Formation rock within the viticultural area, which contributes to the region's distinct terroir, to bedrock-alluvial contact to the east.

The southern and southwestern portions of the Paso Robles Willow Creek District viticultural area boundary follow various roads, streams, section and range lines, and straight lines between marked points on USGS maps to approximately follow the contact of the less resistant Monterey Formation units in the Paso Robles Willow Creek District viticultural area, with a more resistant unit of the Monterey Formation to the south.

The historian J. Fraser MacGillivray describes the motivations of early settlers as follows: "The southwest portion of the 26,000 acre Rancho Paso de Robles offered some attractive features.

One historian recounts: "In our dry land areas, which most of the local fruit and nut acreage was and still is, walnuts became the major tree crop.

[4] The climate of the Paso Robles Willow Creek District has significant maritime influence due to its location near gaps in the crest of the Santa Lucia Range and its high elevations.

The cool climate of the Paso Robles Willow Creek District viticultural area increases the ripening period for grapes, resulting in longer hang-time to develop flavors, with harvest dates approximately two to three weeks later than in other parts of the Paso Robles viticultural area.

Soil orders include Mollisols (where surface humus is abundant under woodlands) and younger, poorly developed Entisols on steep slopes.

The soils in the Paso Robles Willow Creek District viticultural area have modest nutrient values and low to moderate water holding capacity, and are considered moderately fertile (although, in this mountainous region, fertility is also a function of slope stability, which influences soil depth).

These soil characteristics create challenging conditions for winegrapes, and low yields are common for vineyards within the Paso Robles Willow Creek District viticultural area.

Various early settlers of Paso Robles Willow Creek District planted small vineyards along with grain, nut and other fruit crops.

The Pesenti Winery, bonded in 1934 shortly after the Repeal of Prohibition, originally concentrated on regional sales of jug wine, including Zinfandel from vines planted on the estate in the 1920s.