Napa Valley
AVA · Napa County · District 4
27 CFR 9.23 · established 1981-01-28 · last amended 1985-03-29
Heat class III · 1991-2020 normals
Climate normals in three numbers
, Apr 1 – Oct 31
132 GridMET cells cover this region
raw 4 km GridMET would say IV
season rain, Apr 1 – Oct 31
43 mm of it in the , Sep 1 – Oct 31
Warm and cool vintages since 1980
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Rain across the season, and at harvest
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The boundary
Hovering a shaded region names it; a click opens its page.
Measured vineyard area
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Drought categories, year by year
Napa County — not Napa Valley
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What's in the ground
6.3
pH, 1:1 water
13.2cm
, whole profile
98cm
to
Well drained
, dominant condition
Distribution across 232 · mean ◆, median │, p10–p90 bar
Dominant
- 14.6%
- 8.9%
- 8.8%
- 8.7%
- 6.5%
232 map units · soil described over 96.5% of the region’s area · 10.8% is water, rock outcrop or other non-soil · 77% of the described area has a restrictive layer within the profile.
Sand, silt and clay, against every other appellation
Loam
34% sand · 42% silt · 24% clay
Sandier than 14% of California appellations and clayier than 60%. Each grey point is one appellation’s topsoil; appellations nest, so this is a distribution of places rather than of land.
Plus 15% rock fragments by volume, which the triangle does not describe — the three fractions are of the fine-earth material only.
Elevation, slope and aspect
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Producers
A curated roster, not a census — only source-verified entries appear, 2772 published across the atlas.
Bearing acreage by variety
Napa County · District 4
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Price per ton
Napa County · District 4
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The appellation in federal law
The boundary, in the government’s own words (71 words)
(c) Boundaries. The Napa Valley viticultural area is located within Napa County, California. From the beginning point at the conjuction of the Napa County-Sonoma County line and the Napa County-Lake County line, the boundary runs along— (1) The Napa County-Lake County line; (2) Putah Creek and the western and southern shores of Lake Berryessa; (3) The Napa County-Solano County line; and (4) The Napa County-Sonoma County line to the beginning point.