Wine myths
High-altitude wines always have high acidity
“Altitude means cool nights, so high-altitude wine always has bright acidity.”
Altitude lowers mean temperature and often widens the day–night range, both of which help acid retention. It also raises UV exposure and can sit under intense daytime heat, so the outcome is not one-way.
The full answer
Temperature falls with elevation, so a vineyard at 1,500 metres is meaningfully cooler on average than one at 200 metres at the same latitude. Nights in particular tend to be colder, and cool nights slow the respiration that consumes malic acid.
But high-altitude sites in low latitudes can be extremely hot by day. Mendoza’s Uco Valley combines high elevation with intense sunshine, and the resulting wines are not uniformly high-acid.
Altitude also raises ultraviolet exposure, which is associated with thicker skins and higher phenolic content — a tannin and colour effect rather than an acid one.
And latitude does not disappear. A high vineyard near the equator and a high vineyard in Europe are not comparable, because season length differs as well as temperature.
Diurnal range really does bear on acid retention, and it really is one of the reasons high-altitude regions can ripen fruit without losing freshness.
A relationship that has been measured across real samples — a correlation between growing-season temperature and harvest sugar, say — without a single demonstrated mechanism covering the whole path from cause to effect.
What would settle it: A larger or better-controlled study finding no association.
Sources
Sources consulted
- UC Davis Department of Viticulture and Enology — University of California, Davis
- Wines of Argentina / Instituto Nacional de Vitivinicultura — Wines of Argentina; INV
- Research on climate change and viticultural suitability — Peer-reviewed climate and viticulture literature