The Difference Between Cool Climate and Warm Climate Wines

Vineyards can be found on mountainsides and valley floors, in areas that receive plenty of rain or are extremely arid, alongside coasts, or tucked inland. But few aspects of a wine’s origin receive more attention than the amount of heat that its grapes are subjected to during their growing season. Wines are frequently categorized primarily by climate: warmer and cooler regions.

Yet, such a seemingly simple distinction isn’t quite so straightforward.

“It is hard to paint a region overall with such broad strokes to say you are either ‘warm climate’ or ‘cool climate,’” says Laura Jones, winemaker at Skipstone Ranch in Sonoma County’s Alexander Valley. 

The importance of the diurnal shift

The best warm-weather regions aren’t typically marked by unrelenting heat. A balanced wine requires the sugar and depth of ripeness, as well as adequate acidity, to keep it fresh. Wines produced from grapes grown where the nighttime low temperatures aren’t much cooler than the daytime highs come off as one-dimensionally rich and, often, flat. 

Conversely, grapes grown in regions that are too cold would not achieve adequate ripeness, which would result in wines with overly tart and often “green” flavors.

Producers search for balance, whether in the form of a wide diurnal shift — the swing between daytime high temperatures and nighttime lows — or some other aspect. 

“This can be achieved both via your site selection and with practices in the vineyard,” says Jones. “Alexander Valley is a warm region, which makes it well-suited for the Bordeaux varieties we are famous for. Our special positioning in the southern end of the proposed new Pocket Peak appellation provides us with three amazing moderating influences: higher elevations, breezes off the Russian River, and a unique topography from the mountains on our estate. This provides an extra layer of structure and richness to our wines.”

Kimberly Jackson Wickam, co-founder and owner of Jax Vineyards in Napa Valley’s Calistoga American Viticultural Area (AVA), is also focused on the ways in which temperature swings affect her wines. 

“We will drop from 95 degrees [Fahrenheit] in the summer at five o’clock [p.m.], and it’s going to be [in the 50s] by 9:15, so the acidity and structure are consistent,” she says. As a result of Calistoga’s broad diurnal shift, “you get that really complex, robust flavor profile.”

Not all climates are appropriate for every grape variety

When Jackson Wickam decided to produce Pinot Noir, she looked outside of Calistoga because the days there are too warm. Instead, she focused on the Sonoma Coast, specifically the Petaluma Gap AVA.

“We love this [appellation], and it’s the polar opposite of Calistoga,” says Jackson Wickam. “You could not get two more opposing AVAs.” 

The Jax Pinot Noir is produced from grapes harvested in the early morning, to preserve freshness, from Calesa Vineyard, where the average temperature runs between 50 and 60°F. By contrast, summertime in Calistoga tends to be between 60 and 100°F or more. “That shows you how extremely important terroir and AVA are,” says Jackson Wickam. “They’re absolutely everything.”

Characteristics found in warm versus cool climates

Warmer-climate wines tend to be riper than their cool-climate counterparts, which typically possess more mouthwatering acidity. As a result, they often play different roles at the table. Exceptions can be found all over the place, especially when vintage variation is considered. 

“One of my favorite tricks to pull in the pairing with our tasting menu is to pick a varietal that guests might have a certain preconceived notion of, and give them a great example from a much cooler environment than they’re used to,” says Mike Nimmo, beverage manager at Philadelphia’s Messina Social. “Martin and Anna Arndorfer produce a Riesling out of Kamptal, Austria, that is just so much livelier than a Riesling coming from a warmer climate. It’s crisp, clean, and fresh, with loads of green apple and bright citrus flavors that challenge this preconceived idea that Riesling is going to give you a sweet wine dominated by richness.”

The impact of climate change

“Climate can change just about everything when it comes to wine,” says Nimmo.

It’s become increasingly important to explore wines from both warmer and cooler locations to experience how reds and whites are affected by the shifting climate. Winemakers from every region have had to adapt to odd-ball weather changes by switching up grape varieties or harvesting at different times of year. Though these changes come fast and are unprecedented, adaptation to climate has always been a part of the job.

“Grape growing at the top level is always about balance and finding something special that is a moderating influence,” says Jones. “If you’re in a cool region, you might be looking at something to gain some extra warmth. Or if you are in a particularly warm region, you would seek some cooling influence.”