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The Ultimate Guide To Napa Valley

The Ultimate Guide To Napa Valley


Before 1976 and the tasting held by Steven Spurrier, no one was aware of the American wine potential. It’s interesting to see how fast things have changed (and are changing…) since then.

Wine lovers started considering much more American wines and started believing that “the sun wasn’t just shining in France”. Even though everything started with the Stag’s Leap Wine Cellars‘ Cabernet Sauvignon and Chateau Montelena‘s Chardonnay, the wine tasting organized in 1976 had a huge impact on American wine history.

Our humble point of view is that this event changed the overall consideration of the New World wines, not just the American ones. Old World wine drinkers were less skeptical to try wines from Chile, Argentina, but even New Zealand and Australia.

Nowadays, the USA is still growing at a fast pace in terms of wine production. The first AVA (American Viticultural Area) was created in 1980 in Augusta, Missouri, but today the “American portfolio” boasts more than 250 AVAs.

We are happy to see that it looks like American winemakers don’t intend to stop. Recently two new AVAs have been added to their prestigious list, one in Santa Barbara – Alisos Canyon AVA – and two in Washington State – Royal Slope AVA and Candy Mountain.

It’s easy get lost while talking about the countless American AVAs, but we are here today to only focus where everything started: Napa Valley.

Figure 1: One of the two bottles that changed the American wine reputation (greattaste.net, 2016)

Napa Valley: Climate

When talking about such a huge wine region, a systematic approach is strongly recommended to deeply understand why some grapes thrive in certain zones.

Breaking down Napa Valley, considering its climate and environmental factors will help you so much while studying it. Once you know what originates the most important climatic influences in a specific place you will realize that everything becomes much easier.

So it’s very important that you keep your focus levels as high as you can in this small paragraph (take a coffee if you need to…).

If someone asked you what climate California has, you should answer “Mediterranean”. This climate is characterized by a low-temperature difference between the hottest and coldest months. Furthermore, summers tend to be warm and dry and this is the main difference with a Maritime climate. In fact in the latter, rainfalls tend to be evenly spread throughout the year.

The Mediterranean climate is actually one of the biggest Californian strength. Winegrowers can always rely on gentle weather without struggling to reach consistency in their vintages year after year. However, hazards such as drought and bush fires aren’t uncommon (like it happened for the latest vintage 2020…).

Figure 2: The end of a sunny day in Napa Valley (thecrazytourist.com, 2020)

Napa Valley: Environmental Factors

The Mediterranean climate alone wouldn’t be enough to allow winemakers to produce great wines though. In fact, more inland places that can’t rely on other helps given by Mother Nature just produce low-quality wines.

But what are these essential environmental factors?

  • San Pablo Bay: The northern extension of the San Francisco Bay plays an important role in mitigating the climate. Cold Californian Ocean currents can directly pass through, cooling down especially those vineyards to the south of the Valley.
  • Mountains: In addition to San Pablo Bay, you must remember the names of two mountains. Mayacamas mountains, to the west, form the boundary with Sonoma County. Vaca mountains, to the east, separate the Napa Valley from the northern part of the Central Valley. Apart from providing some altitude and good aspects, why are these mountains important? Because they act as a massive funnel where cool air is trapped. When this air meets the hooter coming from the northern part of the valley, it forms a thick layer of fog. And this brings us to the next point…
  • Fog: This natural factor is essential especially for those valley-floor vineyards. Direct sun can’t hit these vineyards and grapes can reach full ripeness while retaining acidity. Without fog, temperatures would be too hot with the consequence that grapes would reach high sugar levels, and wines would lose their elegance and taste “overbaked”. As far as the mountain AVAs are concerned, fog doesn’t play any role. In fact, these AVAs are above the fog line but, due to the altitude which brings the temperature down, they need extra sunlight to fully ripen.

Now that you are aware of the climate and the main environmental factors, we can move on and break down Napa Valley AVA pointing out its main sub-AVAs, with their climate, elevation, and grape varieties.

Figure 3: Some vineyards above the the thick fog line (pinterest.it, 2020)

Napa Valley AVA

First of all, Napa Valley is itself an AVA since 1981. This makes it the second American AVA. Today, the Napa Valley AVA counts 16 sub-AVAs and everyone is somehow distinctive.

We believe that a distinction must be made to fully understand the Napa Valley physiognomy. Therefore we are going to split Napa Valley’s sub-AVAs into two broad categories: the mountain AVAs, and the lower foot-hillside AVAs.

The Mountain AVAs

These are the 5 AVAs located above the fog line. However, we want to be more specific and give you some important information regarding the aspects of these AVAs.

Diamond Mountain District, Spring Mountain District, and Mount Veeder have east aspects. Hence, they are exposed to the early-morning sun.

Howell and Atlas Peak AVAs are both west-facing instead. Therefore, they get full exposure to the hot afternoon sun. In other words, these are the AVAs you must look at if you are keen to drink a fuller-bodied wine with higher alcohol levels.

These are the mountain AVAs from north to south.

AVAClimateElevation (m)Grape
Diamond Mountain District Moderate temperatures
In the summer, they range from 10-32°C
122-671Cabernet Sauvignon, Cabernet Franc
Howell MountainWarmer temperatures due to the strong afternoon sun influence427-792Cabernet Sauvignon, Merlot, Zinfandel, Viognier
Spring Mountain DistrictCool temperature with a lower diurnal range183-792Cabernet Sauvignon, Merlot, Cabernet Franc,
Zinfandel, Chardonnay
Mount VeederCool/ moderate temperature with most vineyards above the fog line152-792Cabernet Sauvignon, Merlot,
Zinfandel, Chardonnay
Atlas PeakCool temperature with a low diurnal range232-792Cabernet Sauvignon,
Table 1: The Mountain AVA (TheWineJokers, 2020)
Figure 4: An iconic bottle of wine from Oakville, that doesn’t need any introduction (livex.com, 2020)

The Lower Foot-Hillside AVAs

These 10 AVAs are those located below the fog line. As we saw, they benefit from the cool Pacific Ocean current channeled in by San Pablo Bay.

A clarification must be made before moving on. The Calistoga and St. Helena AVAs are too far to benefit from this cooling influence. But, thanks to the Chalk Hill Gap in the Mayacamas mountains can provide some relief from the high afternoon temperatures. Here, the higher diurnal range helps retain acidity in the grapes.

It’s finally time to list all the lower foot-hillside AVAs.

CalistogaWarm temperature with a high diurnal range92-370Cabernet Sauvignon,
St. HelenaWarm temperature with a high diurnal range31-217Cabernet Sauvignon, Cabernet Franc,
Chiles Valley DistrictModerate temperature with a high diurnal range186-372Cabernet Sauvignon, Cabernet Franc,
RutherfordModerate/ warm temperature with a distinctive diurnal range0-186Cabernet Sauvignon, Cabernet Franc,
OakvilleModerate/ warm temperature with a distinctive diurnal range0-155Cabernet Sauvignon,
Sauvignon Blanc
Stags Leap DistrictModerate/ warm temperature with a distinctive diurnal range0-155Cabernet Sauvignon,
Sauvignon Blanc
Oak Knoll DistrictModerate/ cool temperature0-244Merlot,
Cabernet Sauvignon,
Sauvignon Blanc,
CoombsvilleModerate/ cool temperature30-300Merlot,
Cabernet Sauvignon
Pinot Noir,
Wild Horse ValleyModerate temperature186-589Cabernet Sauvignon,
Pinot Noir,
Los CarnerosCool temperature0-217Pinot Noir, Merlot,
Table 2: The Lower Foot-Hillside AVAs (TheWineJokers, 2020)

If you pay attention while going to the table, you can realize that the temperatures drops and the climate becomes cooler as we move to the south. As we move to the south?! But wait a second, temperatures should rise in the northern hemisphere, shouldn’t they? Yes, you are definitely right if you think about the latitude. However, this is one of the countless exceptions you might find in the world of wine.

If you look at the map, you can clearly see that especially Los Carneros and Oak Knoll District are the first two AVAs to be fully within the giant funnel created by the two important mountains we previously spoke about (if you don’t remember their names, go back to the environmental factors…!) and the closest to the San Pablo Bay.

This explains why Los Carneros is among the best places in the USA for sparkling wines. Note that as a rule of thumb, places where Chardonnay and Pinot Noir thrive, make great sparkling wines too.

Figure 5: Napa Valley map with all the sub-AVAs (Robert Fukuda, 2016)


If you truly understand what’s written and how to exploit this article, you have your American Visa to land in Napa Valley.

Joking aside, this is a very reliable article we wrote combining knowledge from several books. We are sure pieces of content like this one would allow you to easily pass the WSET 3 with Distinction.

Apart from the priceless value of it, we hope this article brought to your attention how important the environmental factors might be when it comes to wine growing.

That’s the beauty of this complex world after all. Understanding the basic principles would allow you to create automatic links that you will never forget (because you won’t even need to remember them after you got them).

There is nothing left to do then. Just save the article, let us know in the comment if you want to see more content like this one, and last, but by no mean least, place an order with the amazing wines from the AVAs you liked the most according to the explanation.

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