Last year’s US$3.1 was the first time the auction, considered a barometer of the popularity of certain wineries and the state of the economy, broke through the $3m barrier.

The average wholesale bottle price was US$160.75, an indicator of the quality of the 2011 vintage, one of the coolest and most difficult of recent years which produced low yields of highly-regarded wines, praised for their elegance and structure.

Auctioneers Ursula Hermacinski (pictured) and Fritz Hatton let three hours of raucous bidding, with delegates occupying the floor and winemakers sitting nervously around the sides waiting for their lot to come up. A total of 67 successful bidders out of 1000 attendees bought 207 lots of wines – the vast majority from 2011 – made especially for the event.

With lots having to be between 60 and 240 bottles, winemakers regard the auction as an opportunity to experiment with limited production and create unique blends.

Blends included almost every major variety grown in Napa: Cabernet Sauvignon, Cabernet Franc, Pinot Noir, Sauvignon Blanc, Merlot, Chardonnay, Malbec, Petit Verdot, Petite Sirah, Semillion and Syrah.

Chateau Montelena, for example, blended and co-fermented 2010 estate Cabernet Sauvignon and Petite Sirah for the first time, while others focussed on particular clones or minute parcels of vineyard.

For buyers and consumers the auction is a measure of demand for the latest vintage. One retailer, Rick Naifeh of Premium Brands in Oklahoma, had just bought a 10-case lot of Yountville’s Tamber Bey for US$9,000, and 20 cases of Honig for US$30,000.

He said he ‘often got the year’s best deals’ at the auction and would sell on most of what he bought, adding he was particularly pleased with the 2011s. ‘It was a rough vintage but everything I tasted I enjoyed.’

Top earning lots included Shafer Vineyards’ five-case lot from its Sunspot vineyard, which forms the backbone of the celebrated Hillside Select, for US$50,000, Derencourt California, US$36,000, a lot from Saintsbury’s Brown Ranch in Carneros for US$36,000, and Rombauer Vineyards Atlas Peak for US$40,000.

Other high-earning lots were a joint lot from Bevan Cellars and Chateau Boswell Winery, Reynolds Family Winery, Keenan Winery, Kapcsandy Family Winery, Duckhorn Vineyards, Silver Oak Cellars, Hourglass, Vine Hill Ranch and ZD Wines.

The 2011 vintage in Napa – and neighbouring Sonoma Valley – was considered extremely difficult for winemakers. A cool growing season with poor fruit set was compounded by heavy rains at the beginning of the harvest in early October, bringing problems of rot. Some winemakers said it was the first time they had seen botrytis in Napa Cabernet.

Vintners were torn between harvesting before the rains and risking under-ripeness, or bringing in grapes diluted by rain. French winemaker and consultant Stephane Derenoncourt, of Derenoncourt California, said he personally had picked after the rain. ‘I can manage dilution – I work in Bordeaux, after all,’ he said.

It was a vintage where vintners had to use all their skills in the vineyard and winery. ‘I wouldn’t want to live through that vintage again,’ Christopher Carpenter at Mount Brave winery in the Mount Veeder appellation told Decanter.com. ‘I had to remember everything I learned at Davis.’

Profits from Premiere Napa Valley, which was founded in 1997, go to Napa Valley Vintners, a non-profit organisation which represents 450 Napa Vintners. Auction Napa Valley, held in June, benefits Napa County charities.