Many wine fans believe California’s weather is so consistently warm and sunny that its wines vary little by vintage.

“It’s not true,” said Mark DeVere, a master of wine representing the Robert Mondavi Winery at the South Beach Wine and Food Festival in Miami Beach in February.

“We can get our grapes ripe every year, unlike Europe, which is colder,” he said. “But there are still differences in the years. The fruit might be up one year, the acid the next.”

DeVere demonstrated some of the differences at a seminar sponsored by Wine Spectator magazine at the festival. It was a “vertical” tasting, featuring the Robert Mondavi Cabernet Sauvignon Reserve from Napa Valley from the years 1985, 1994, 1998, 2000, 2006 and 2009.

It was an extraordinary event, with some wines that today can be found only at the winery, or in private collectors’ cellars.

“This is a treat for me too,” said DeVere. “I don’t get to do a vertical like this very often.”

Mondavi wines were a good choice for the demonstration, since the winery has been around since Mondavi founded it in 1966.

“Mondavi really brought wine into America,” said Tom Matthews, Wine Spectator’s executive editor. “I doubt there’s any wine fan who hasn’t heard of him.”

He went on: “This is an opportunity to see how wine evolves over time and how the weather and winemaking during different vintages changes it. The younger wines have intense color and fruit and structure. Older wines become more subtle, silkier.

“Also, if you have them in your cellar, this is a chance to see if it’s time to open them.”

The oldest wine in the vertical tasting, the 1985, was losing its vibrant purple color, but retained lively fruit flavors as well as more resolved, complex flavors like leather and earth. “You can’t get these flavors in a young wine, DeVere said. “They come only through age. Mondavi wanted gentle wines, with layers of flavor – with power, but not an assault on the palate.”

The youngest wine, the 2009 current release in wine shops, was so powerful that DeVere quipped: “It’s as youthful as you can decently serve.” He declined to say which vintages are ready to drink, which need more time. “I hate to say when is the best age. It’s a matter of personal taste.”

(The 2009 reserve cabernet sauvignon is on sale in shops nationwide for $135. Some of the older vintages can be found at auction, or by visiting the winery in Oakville, Calif., a spokeswoman said. The older vintages would sell for $165, she said.)

Vertical Tasting of Robert Mondavi Cabernet Sauvignon Reserve:

•  1985 Robert Mondavi Winery Cabernet Sauvignon Reserve, Napa Valley, Calif.: color turning to mahogany, wide clear rim, aromas of dried roses, still lively flavors of black raspberries, cocoa, earth and leather, with delicate, resolving tannins and acids, sweet finish; overall, a complex wine.

•  1994 Robert Mondavi Winery Cabernet Sauvignon Reserve, Napa Valley, Calif.: more youthful, darker hue, with aromas and riper flavors of blackberries and milk chocolate. Said DeVere: “This shows an important evolution in winemaking. By this time it was the winemaker, not the vineyard manager, who decided when to pick. There was more interest in the vineyard, and the wines became more subtle. The 1985 was more of an Old World style, with more acid.”

•  1998 Robert Mondavi Winery Cabernet Sauvignon Reserve, Napa Valley, Calif.: Dark hue, with delicate black plum and cinnamon flavors, powerful tannins and a long finish. De Vere: “This was a cold year, and it was hard to get the grapes ripe.”

•  2000 Robert Mondavi Winery Cabernet Sauvignon Reserve, Napa Valley, Calif.: darker hue, intense black raspberry and black plum flavors, with hints of mocha and powerful tannins. DeVere: “It was not a great year, but we were among the vineyards that picked before the rains came.”

•  2006 Robert Mondavi Winery Cabernet Sauvignon Reserve, Napa Valley, Calif.: ultra-dark hue, bursting with black raspberries and bittersweet chocolate, big but ripe tannins, youthful and concentrated. DeVere: “By this time Mondavi was using its new fermentation facility, with oak fermentation tanks that softened the tannins but kept the powerful fruit.”