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urban planning and design
Shifting Terroir:
Wine Country, Climate Change,
and the Geography of US Viticulture
How does climate change reshape the geography of viticultural suitability across the United States, and which regions stand to gain or lose as growing season temperatures rise?
Project Type
Academic
(Individual)
Instructor
Jonathan Stiles
Tools
ArcGIS Pro, Illustrator,
Photoshop, Python, InDesign
Completed Period
Spring, 2026
Viticulture
noun (/ˈvidəˌkəlCHər/) :
the cultivation or culture of grapes especially for wine making
Of all the factors that determine where wine grapes can be grown, temperature is the most consequential. While soil, aspect, precipitation, and viticulture practice all shape wine character, it is the thermal regime of the growing season that sets the outer limits of what is possible. Globally, viable winegrowing is concentrated within a narrow band of average growing season temperatures (GST), roughly 13 to 22°C (approximately 55 to 72°F). Below this threshold, fruit cannot ripen reliably, and above it, excessive heat degrades acid structure and aromatic complexity, ultimately pushing regions outside the range of quality wine production entirely.
The Winkler Index, developed at UC Davis, operationalizes this thermal logic by classifying wine regions into five zones based on accumulated growing degree-days. Jones translated this five-zone structure into GST ranges, making the classification directly applicable to gridded climate data like PRISM. This project uses GST as its primary climate metric. Critically, the impacts of warming are not linear but threshold-driven. A region warming from 15°C to 16°C expands its varietal options, but one warming past 22°C (72°F) exits viable suitability altogether (Jones, 2006).
The geography of warming is a story of divergence. Established, economically dense wine states in California face structural pressure, while frontier wine states in the north stand to gain under at least moderate warming. This project maps that divergence at the state level and grounds it in the distribution of licensed producers, asking not just which states cross climate thresholds but which states carry the greatest economic exposure when they do.
A single zone shift redraws what is economically viable to grow. Moving from Zone 1 to Zone 2, for instance, means transitioning from Pinot Noir to Merlot.
1)
Winkler Climate Zones,
Baseline (1991-2020)
Methodology
2)
Winkler Climate Zones,
Projected (+2°C / +3.6°F)
3)
Kernel Density of
Licensed Winery Locations
Where American Wine is Made,
2012-2014 (Gallons)
4)
Spatial Clustering of
Winery Counts by County, (LISA)
winery density index
(relative)
winery concentration patterns
5)
Wine Production by State,
2024 (Gallons)
California alone produced 78.5% of total US production in 2024.
6)
Magnitude of Winkler
Zone Shifts Under a +2°C
7)
Regional Detail,
Southern California
8)
Regional Detail,
Maine
9)
Where Temperature Explains
Wine Geography, (Local R², GWR)
temperature’s explanatory power
The highlighted borders in Map 7 and 8 mark the current limits of viticultural suitability, overlaid on the projected +2°C raster. In Southern California, territory that already sits at the thermal ceiling expands significantly beyond the viable range. In Maine, an entire region that was previously too cold crosses into Zone 1 suitability for the first time.
The spatial analysis reveals a country in viticultural transition and a planning challenge hiding in plain sight. Wine production shapes land use in ways planners directly engage with, influencing agricultural zoning decisions, directing infrastructure investment, anchoring rural tourism economies, and driving property values across millions of acres. Therefore as climate shifts the thermal foundations of where wine can be grown, these planning implications follow.
The baseline Winkler classification in Map 1 confirms that viable territory for growing wine is concentrated along the Pacific Coast and in scattered pockets of the Northeast. This pattern is reinforced by the KDE (Map 3) and LISA (Map 4) analyses, which identify coastal California and the Boston-to-Washington corridor as the two dominant hubs of licensed winery activity. The proportional dot in Map 5 grounds this further, as California alone produced 508 million gallons in 2024, representing 78.5% of national output. This imbalance concentrates the economic stakes of climate risk in a single state. Notably, winery density does not translate directly into production volume. The Northeast and Texas both show relatively high winery density in the KDE surface, yet Texas has never appeared in the top five producing states since the TTB data became available in 2012. For this reason, density reflects the presence of an industry, but it does not measure its scale.
Texas presents a particularly revealing case. Even before any warming is applied, much of Texas already sits outside the viable growing range, yet it sustains a substantial winery presence. The GWR local R² surface assigns Texas some of the lowest values as seen in Map 9. This explains how temperature contributes almost nothing about where wineries locate there. Perhaps other factors like tourism, cultural identity, infrastructure investment, and consumer demand are doing the explanatory work that climate cannot. Texas is the clearest evidence in this dataset that the wine industry does not go where climate permits, but goes where conditions are created for it.
Under a +2°C warming scenario, the hexagon tessellation in May 6 highlights the redistribution of suitability visually legible across the continental United States. The overall picture is one of southward exit and northward entry, but the details complicate the headline. The southern tier exits the viable range in a continuous band, yet the KDE surface shows that
much of this exiting territory in states like Oklahoma, Arkansas and Tennessee already has little to no winery presence. It is therefore important to note that though the climate loss is real, the economic disruption is limited where the industry never took root. Napa Valley, the symbolic and economic core of American wine, remains within the viable range under the warming scenario, shifting mostly into Zone 4, with only a small area near Black Butte Lake in Northern California becoming too hot, affecting just two licensed wineries.
Southern California was selected for the inset in Map 7 because it concentrates significant winery activity visible in the KDE, and also because it anchors the geographic argument of the entire poster. Wine growing will move, not figuratively but literally, from the southwestern corner of the country to the northeastern corner. The southern California inset and Maine inset (Map 8) are two opposite ends of the same story. Yet the Maine inset also reveals the infrastructure gap that makes this transition a planning problem rather than a natural market correction. The areas entering Zone 1 suitability in Maine currently have almost no winery presence. Since climate will become permissive, the zoning, investment, and institutional frameworks that turn climatic permission into an actual industry will need to exist.
This gap is even more pronounced when comparing the LISA clustering map with the hexagon tessellation. States across the northern Midwest like North Dakota, Minnesota, and Wisconsin, and western states including Wyoming, Idaho, and Montana will gain viable growing conditions under +2°C. Yet the LISA map identifies these same areas as Low-Low clusters, wine deserts surrounded by wine deserts, with almost no winery density in the KDE surface. Climate suitability is a necessary condition for a wine industry, but the findings proves that it is not a sufficient one. The GWR local R² surface confirms this at the county level, in which climate sets the boundaries of what is possible, but again, market access, land costs, and regulatory history determine where the industry actually goes. These are precisely the factors planners are positioned to shape.
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