Microclimates

[jbonne]

I have always found chardonnays from Monterey, Santa Barbara and Edna Valley to be distinctly different in basic fruit character than Napa and Sonoma.  Crisper, more green apple fruit, and usually styled with less oak.

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hey, is there anyone who lists the heat/sunshine indices of the various Calif. appellations? always seemed like something it'd be fun to compare.

[JohnL]

I agree--it would be interesting.

I am sure Cal Davis has the info!

I will poke around though I am sure one of the

grape growers out here will have access!!!

[Rebel Rose]

Grapes do not grow effectively below 50º, so degree-days have been defined as the total summation of average degrees above 50º. The regions are defined as Region I, the coolest areas, which are areas exhibiting 2,500 or fewer degree-days. These areas also tend to be attractive for vegetable production. Region II is defined as 2,500 to 3,000, Region III as 3,000 to 3,500, IV as 3,500 to 4,000, and V, the warmest region, are those areas above 4,000-degree days.

In the Central Coast, Region I locations include Bonny Doon, Santa Cruz, and Santa Maria. Region II locations are Atascadero, Soledad, San Luis Obispo, Santa Barbara, and Hollister. Napa is also a Region II location. Region III locations are Paso Robles, Santa Margarita, and the Pinnacles (Chalone). Region IV locations are Nacimmiento and San Miguel. Region V locations are typically Central Valley or other interior regions.

Taken from an article at

California Wineland:

The unique climatalogical conditions of the California coast create an interesting phenomenon in this regard. The coolest Regions, I and II, are also typically the most temperate. The lower maximum temperatures in these areas are typically mirrored by higher minimum temperatures, creating an average annual temperature that is relatively flat.  Conversely, in the warmer King City area, average maximums reach 85 in July and September, but minimums drop to 35 in December and January. Paso Robles is even more volatile, with highs of 98 recorded in July, and lows of 32 in December. Thus, the Region I areas tend to be more moderate, or temperate, with fewer extremes of either highs, or lows.

South of Monterey County, we enter San Luis Obispo County, and the huge (614,000 acres) Paso Robles AVA. The warmest of the established AVAs, this area perches high atop the ridges of the Santa Lucias, yet the ocean's influence still produces cool nights, allowing for some spectacular vintages. The geography of the area allows for the broadest variety of rainfall, from 8 to 45 inches. The hills west of the city are home to some of the oldest Zinfandel on the coast. These older, dry-farmed vines can produce spectacular wines, albeit in only small quantities. Locals are watching with interest the Beaucastel Estate, a recent joint venture of the French Perrin family and Robert Haas, another of the coastal ventures into the traditional Rhône varieties. Some local vintners are displaying optimism about recent experiments with Sangiovese.

This information is a little out of date, as the western part of Paso Robles is more Region II, with highs around 88 and winter lows in the 20s. This year is a little extraordinary in terms of precipitation. The Vineyard Drive/Adelaida Hills area has already received 43" of rain.

[JohnL]

Thanks Rebel Rose!

This stuff is really interesting.

(I should have been a farmer!)

I bet somewhere at davis there are color maps!

Your post points out that "terroir" is not just about soil.

Weather is really important--maybe most important!

[jbonne]

thanks so much, Rose. this is terrific data, even if slightly aged.

also curious how subappellations break down. Napa may be Region II, but I imagine that Stags Leap and Howell Mountain are probably at either end of that, if not in different categories altogether.

[Rebel Rose]

You guys really find this interesting? Cool.

I found a little more information in my copy of General Viticulture. The data above is based on annual measurements that include the dormant season. GV sorts the areas below based on degree days from April to October:

Climate Region I (very cool and vegetative):

Aptos and Santa Cruz

Peachland (Sonoma County)

Salem and Roseburg, Oregon

Trier, Germany

Coonawarra, Austraila

Region II:

Contra Costa

San Luis Obispo

Santa Barbara

Napa (Napa County)

Santa Rosa, Mote Rosso Vd., and Sonoma (Sonoma County)

Grants Pass, Oregon

Yakima, Washington

Asti, Italy

Melbourne, Australia

Region III:

Oakville, Calistoga, St. Helena (Napa County)

Pinnacles (San Benito County--home of Chalone)

Paso Robles

Milan, Italy

Region IV:

Escondido (San Diego County)

Gallo Vyd (Merced County)

Lodi

San Miguel (warmer region in the north of Paso Robles)

Sidney, Australia

Florence and Venice, Italy

Region V:

Fresno and Bakersfield

Palermo, Italy

Perth, Australia

Peking, China

Shiraz, Iran

Page 70: "Wines of best quality are usually produced in the hot years of the coolest regions, whereas in the warm regions the cool years produce the higher-quality wines."

[jbonne]

You guys really find this interesting?  Cool.   

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absolutely! it's not a perfect measurement, but when you factor in a heat index with hangtime, winter dormancy, air drainage, &c., you begin to see how wine styles really do reflect the climate of their terroir.

now i'm curious where Bordeaux, Burgundy, Alsace and the Rhone fit into the mix. and of course, how the Napa microclimates factor in.

the cool climate/hot year-hot climate/cool year is something i'm hearing more often. Pierre Rovani was saying something to that effect earlier this year, though it was in the context of defending big, concentrated wines. a hot-year Bordeaux is still a pretty different animal than an average-year Napa Cab.

[Rebel Rose]

Good point. While "air drainage" might sound funny to some, north/south valleys will have different air movement patterns than east/west. In California, east slopes (facing away from ocean breezes) may or may not have room for air to drain away into adjacent valleys. Will hot days become humid and sticky with no air movement, resulting in disease and mildew? In early spring, will frost settle on the slopes without warmer Pacific air to wash it away?

Another factor is sunlight. Although heat ripens grapes, plants also pace their growth and development according to the hours of sunlight in a day. Grapevines will begin to "shut down" late in the harvest season. Even if the soil is moderately moist, and temperatures benign, when days begin to shorten, grapevine leaves will redden, dry and fall. A stressed or overcropped vineyard will shut down earlier than most, but even so, one autumn could feel like spring, but the vines will still respond to the changing cycles of light. So latitude affects growing seasons and grape development, even outside of the related temperature patterns.

Diurnal temperature swings also have a marked effect. In some areas, grapes are warmed by 80 degree days, but nights cool to only 60--in other regions, days may warm to 95, but the grapes are cooled by nights in the low 50s.

[Rebel Rose]

Here's a link to a previous discussion on terroir. Beware, it's not entirely civilized. (Which is why it should be resurrected.)