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Climate change = coastal cooling


I blogged a year ago that I don’t think coastal California is warming up. “It’s almost official — coastal California is getting colder, not hotter,” I wrote.

Well, now it is official.

Last week, the San Francisco Chronicle reported that scientists have concluded that “Global warming is warming the interior part of California, but it leads to a reverse reaction of more fog along the coast.” And fog, as we all know, is what makes the California coast cool during the summer months.

The article continues: “…colder summers are indeed in store for parts of the Bay Area.” And with the Pacific waters even colder than usual, the coast is in the midst of a chill-down of unknown length. The California Current brings polar water southward, past Washington and Oregon and off our coast, which is why swimming in the Pacific in Northern California is not advisable without a wet suit, even in high summer.

Just where the boundary line is between “interior” and “coast” is elusive. Sacramento is definitely interior. So is Livermore. Is Napa Valley interior? I don’t think so, especially the southern parts, which are more open to the maritime influence than Livermore. Even Calistoga gets some fog and maritime influence, which comes in from the Russian River Valley through a gap in the Mayacamas. (Bo Barrett, of Chateau Montelena, pointed that out to me.)

This past May was the foggiest in 50 years in and around the Bay Area. And June, as everyone knows who lives here, was a real chiller. Yes, we had mini-heat waves in both months, but by the end of June, everyone was talking about how cool it’s been. Even when the sun was out,  temperatures had a hard time busting out of the low 60s here in Oakland, and the mid-70s in wine country. For much of June, the weathermen were telling us  temperatures were running 20 degrees below normal inland. My local TV weatherman said June was the coldest in more than 100 years.

Actually, the fact that the coast is cooling was reported nearly a  year ago, in Scientific American magazine, which said that “A group of northern California scientists have found a new bend in the Gordian knot of global warming: coastal cooling…as temperatures rise in California, so do pressure differences that control cool Pacific winds. That means higher temperatures inland create lower ones at the coast.” One of the scientists made this interesting remark: “…the findings bode well for California’s wine regions…”.

I don’t know what exactly this means for coastal California’s wine regions, from Santa Barbara north to Anderson Valley. But it does seem like it’s not going to get as hot as people had feared. As for the Central Valley, if you think it’s hot there now, just wait. (Should be great for the grapes…)

By the way, as I write his on Sunday evening, the forecast is for a warming trend this week. Temperatures might hit 100 in the hotter inland valleys, including Napa-Sonoma. I realize the irony, in light of what I have written. But it doesn’t undermine the thesis: wine country is cooling off.

  1. A couple of years ago I saw a warming prediction map that suggested this same thing – cooling or little change along the coast – with a thumb of pushing up from the Bay into Napa/Sonoma. I’m kicking myself for not retaining the reference, nor have I been ablel to find it again. Anyway, yeah, we just planted more Pinot.

    Of course some simulations predict that past a certain point the circulation of those cold ocean currents will be disrupted – then all bets are off.

    So far this season’s heat acumulation is like 1998, but this has been the WINDIEST season I can remember.

  2. I am surprised it has taken these brainiacs so long to figure out the obvious. Anyone who lives near San Francisco is familiar with the term “natural air conditioning”, meaning the fog. Mark Twain knew about it, and Herb Caen (anybody here old enough to remember Herb Caen) wrote about it often.

    The simple fact. When the interior heats up, the fog builds up along the coast and cools us off. All the charts that show Napa losing its ability to grow good grapes are a reflection of a model that does not understand the dynamic we have here. It is why we can live in an area that has a Mediterranean climate and yet not ever need air conditioning.

  3. Steve,
    As a surfer, I am very interested in what happens along the coast, especially because the older I get, the less I am inclined to stuff myself into a wetsuit, boots and a hood just so I can stand the low water temperature in our local break. Here I was hoping that Global Warming will allow me to soon plant a Papaya tree in my yard and maybe replant the Merlot vineyard to something like Passion Fruit or Guavas.

    I do believe that it is a mistake to draw long-term conclusions from what (may be) short term trends. This reminds me of the story about the Elephant that walked into a village of blind people: One person grabs a leg and says “it is thick and round” the other grabs the tail and says “No, it is thin, long and wiry” the third grabs the ear and says “You fools! It is flat and Broad”.

    My research shows that we have been in a warming trend since the end of the last ice-age (roughly 17,000 years ago) and I believe that regardless of local trends (that may last a decade or two..) it may be a good time to buy some land in Anchorage for some Cabernet plantings. Now if I could only get consumers to embrace Syrah from the Upper Middle Reach of the Russian River Valley, where it is way to warm for great Pinot.

  4. Hey Oded, I haven’t tasted your Syrah for a year or so, but you were doing some pretty interesting things. Would you include Rochioli in Upper Middle Reach or are you talking more about as you approach West Dry Creek Road?

  5. The bad news: we’re all going to die from climate change.
    The good news: at least we’ll have more balanced wine!

    My overall impression is that many grapes aren’t grown in the sorts of high risk, high reward marginal climates that make the most compelling wines. But it seems near term the climates will marginalize themselves!

    It’s kind of interesting to see how perceptions of CA wine shift. It’s taken me a while to realize the concept of vintage is important. In France, it seems grapes are usually under ripe or ripe, with a rare case of over ripeness. In CA, over ripeness is the main issue, and under ripe grapes are the rarity. Perhaps all the really big wines of the early 2000s were just the result of a string of disastrously bad vintages that lacked balance (though most people do prefer jammy to vegetal), while the recent “trend” of more balance is primarily due to the weather.

  6. Greg, I think that cooler vintages have resulted in more balanced wines. Also, vintners and growers are looking for ways to achieve ripeness at lower sugar levels.

  7. “As for the Central Valley, if you think it’s hot there now, just wait. (Should be great for the grapes…)”

    Maybe so for the flatlands, Steve but our handy little satellite reporting device monitored by Richard Brockmeyer for the last six years proves a (however temporary) cooling trend here in the Central Sierra foothills of eastern Madera County.
    By the way, are not Calistoga’s heat summations (from the Mendo growers ad) still upwards of Region IV ?

  8. Morton Leslie says:

    1934 was the warmest year on record for the U.S. according to NASA. 1998 the second. I don’t know about 1934, but 1998 was cold here in the valley. Interestingly, NASA with big fanfare once designated 1998 the warmest year on record and, thereafter, made equally startling press releases about the acceleration of global warming. Then in 2007 an amateur, Steve McIntyre, began examining NASA’s “corrected” temperature graph. He discovered an upward discontinuity of one deg C in wintertime and 0.8 deg C annually. He checked the monthly data and determined that the discontinuity began on January 2000. He published the discovery of the apparent Y2K error by NASA on his blog. Quietly without the fanfare of their last decade of press releases, NASA acknowledged the error and revised their data of nearly a decade downward.

    One of the reasons the “brainiacs” haven’t figured this out is that many lack the common sense gene. It isn’t that just that they can’t see an obvious discontinuity in their data, they don’t see the problem with using contaminated data.

    All you need to do is go to their weather stations in Napa at Napa State Hospital or the Napa Airport to see why they might be deficient. If you aren’t familiar with the changes that have occurred around those stations the last two decades, the housing, mall and college construction adjacent to the hospital or the industrial park built around the Napa airport have provided most of the local “global warming” effect. Flat empty fields cool quickly once the sun is down, concrete and asphalt retain heat. This accounts for the warmer night time temperatures around the weather stations that the brainiacs interpret as changes to our local climate.

    NASA will tell you the data from these weather stations is “corrected” by applying a factor to allow for the urbanization, but NASA will not publish the computer source code and formulae used to calculate the trends in their data, nor the corrections used to arrive at the “corrected” data. (is anyone asking why, given they work for us?)

    Fortunately winegrowers pay attention to our own weather stations in the vineyard that thanks to the ag preserve lack the concrete-asphalt generated climate change and the need for “correcting” data.

  9. Perhaps NASA uses the same secret code as the Farmer’s Almanac?

  10. Morton Leslie says:

    I wouldn’t be surprised if Al Gore doesn’t provide the code. About 78% of NASA’s ground stations have been documented by volunteers who photograph them and their location and post them at So far 61% of NASA’s stations are documented to be within 10 meters of an artificial heat source. 8% have been found to be immediately adjacent to artificial heat sources. Napa Hospital, Healdsburg, and Santa Rosa are in that latter category. For a laugh go to the web address above and click on “Odd Stations”

  11. Months ago in my blog at our website,, i noted that our highs were getting higher(our westside Paso mountain vineyard) and our cold valley vineyard lows were getting colder…and later, into June with temps in the mid 30s on some nites. So we have simultaneously, in one vineyard, the higher, more sustained highs in the mountain vineyard(Cab, Syrah, Merlot) and lower, more sustained lows in our cold valley vineyard. Bizarre doesn’t even come close to describing this weird juxtaposition. We have obviously grafted over the cold valley Cab to Pinot and Sauv Blanc, much more suited for the coastal lows. The mountain vineyard Cab and Syrah is loving the higher highs, so in spite of climatic changes, we have adapted to what we have been given. Necessity is the mother of invention…or in this case, adaptation.

  12. Steve and Gang,

    I like this thread, one big hurray for individuality WITH civility. To answer Steve’s question about Pinot Noir and Russian River micro climates:
    It is the war of the clones… I am on record warning growers that most (if not all) the Dijon clones were selected in BURGUNDY for early maturity. Couple that with forced low yields (do not get me started on that controversial topic) and rootstocks that shut down during a heat wave and never recover (resulting in raisining) and you better be ready to harvest your Pinot in Late August or early September. Some of the older clones (and good old AXR…) had no problem surviving the heat waves without going over 24 brix or losing all their natural acidity (The martini Clone was one of my personal favorites). Alas, very little color to some of these old clones so that when “Bigger and darker is better” came to dominate American wines – everyone switches to Dijon Clones.

    I guess we are all right, there is nothing “wrong” with hugely extracted and over the top Pinot Noirs (other than those that blatantly lie by saying 14.2 % Alcohol but when I take them to the lab they show 16.7%). As for me, I believe the monoculture of Dijon Clones HAS changed the rules and that we are picking earlier in the season AT HIGHER BRIX LEVELS in the areas that are East of the first coastal hills, so in a way, yes, we have made parts of the RRV appelation too hot for the Pinot we are growing, even down by Moshin and further towards Korbel…

  13. What a pitiful bunch of comments. Australia will cease to be a wine producing country, Spain is in peril, Bordeaux will be parkerized au natural; yet our little slice of the wine world, the Cali coast, will experience a modest bump of quality. As the world proves unproductive for the most basic agriculture, we might yet enjoy wine.

    Each of us an ugly little Nero.

  14. Ken–

    This is a little over the top. The conversation has not been about global warming as a problem worldwide, but about what will happen in coastal California. There may be some who still doubt the phenomenon or who think that human activity has played no role in global warming, but I suspect that most of us here are concerned and aware.

    Whether you are right or wrong about the impacts, we can all discuss those questions with civility. I can’t see how the use of words like “pitiful” or “ugly little Nero” helps your cause, which, by the way, is not uniquely yours.

    Respectfully submitted,
    Charlie Olken

  15. Thanks, Charlie. Ken – ditto what he said. Following some of your recent comments – are you playing the happy agent provocateur or are you starting to live under a bridge? 😉

    Oded – great comment re: Dijon clones and their impact on the direction of California Pinot. As of this year we have completed our Pinot plantation on our own vineyard: 49.8% Dijon clones, 50.2% “California Heritage” clones/selections. The Dijons are in the cooler spots. We will farm these differently and and vinify them separately. We won’t be trying to make Cab-colored syrupy cocktail wines out of either, but I expect very different outcomes.

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