Don't sleep on the importance of Paso Robles' chilly nights
July 10, 2025
On Monday, I got back from two weeks of vacation in Italy. It was a lovely trip with family celebrating a milestone birthday for my mom. I come back having felt like I unplugged successfully from work, which I'm not always great at doing. Our destination within Italy was Puglia, and specifically Salento, in the heel of the Italy's boot, a rural province studded with relics from a complicated cultural past that includes influences from Greece, Rome, and Normandy:
Italy was relaxing and beautiful, but it was also hot. Days were consistently in the upper 90°s F, and if you weren't at the beach or the pool, the heat was relentless. A big reason for this was that the nights didn't really cool down much, only to the low 80°s F, so even in the relatively early morning it was toasty. When we got home, walking out of the San Francisco airport into a cool afternoon breeze felt like a revelation. And the night we got home, Paso Robles got down to 42°F and I had to pull out a comforter as we were sleeping with our windows open.
Our re-entry into California drove home to me one of the principal things that makes the Paso Robles climate so noteworthy: its massive drop in temperatures at night during the growing season. It's easy to pay attention to how hot it can be during the day (though we've had a remarkably mild summer so far, with our average high temperature in June and July just 88°F) but while daytime temperatures are more salient to most people than what it's like at 3am, the grapevines are out at night too. And the degree to which the temperatures drop here at night is a lot greater than what you see in Europe. Our average nighttime low since June 1st has been a remarkable 47°F, fully 41°F lower than the average daytime high.
Now Salento, so close to both the Adriatic and Ionian Seas, isn't where the grapevines that we grow originated (though I did enjoy several delicious Vermentinos on our trip). It is quite a bit hotter, and sees less daily variation, than a place like Avignon, the nearest city to Chateauneuf-du-Pape where I could find historical weather data. So I pulled the maximum and minimum temperature data from Avignon since May 1st as a comparison to what we've seen here so far. It's still been quite different:
The average high since May 1st (Tablas Creek: 85.5°F, Avignon: 84.9°F) is nearly identical at the two locations. But the average low temperature is very different (Tablas Creek: 45.3°F, Avignon: 60.8°F). In fact, Avignon hasn't had a single night in that stretch drop down to what our average has been here. That has meant that our average temperature since May 1st has been 7.4°F cooler than in France (Tablas Creek: 65.4°F, Avignon 72.8°F).
Now this year has been mild here in California and hot around the Mediterranean, so there isn't usually a 7.4°F difference between the average summer day in Paso Robles and Avignon. But there is still a difference. Last year, which was very hot here, still saw average May-September temperatures that were 1.6°F cooler at Tablas Creek. 2023, a cool year here in California, saw average temperatures 7.2°F cooler here than in Avignon. In 2022, which was hot in both places, our average temperatures were 4.2°F cooler. In 2021, we were 2.1°F cooler. And in 2020, our average day was 2.3°F cooler. Here's the data in table format if that makes it easier to parse:
Year | Average High: Avignon | Average Low: Avignon | Average High: Tablas | Average Low: Tablas | Difference |
2020 | 84.2°F | 59.8°F | 88.8°F | 50.6°F | -7.4°F |
2021 | 83°F | 60°F | 88.6°F | 50.2°F | -1.6°F |
2022 | 87.2°F | 63.4°F | 90.2°F | 51.4°F | -7.2°F |
2023 | 86°F | 61.4°F | 83.6°F | 49.4°F | -4.2°F |
2024 | 83.2°F | 60.2°F | 90°F | 50.2°F | -2.1°F |
2025 | 84.9°F | 60.8°F | 85.5°F | 45.3°F | -2.3°F |
Average 2020-2025 | 84.8°F | 60.9°F | 87.8°F | 49.5°F | -4.1°F |
In summary, so far this decade, the average summer day at Tablas Creek has been 4.1°F cooler than in Avignon. That is true despite that the average summer high has been 3°F warmer, because the average night here has been 11.4°F cooler. So while this year has been an extreme example of the phenomenon I'm describing, it's not a one-year blip.
Note that the above information only covers the core growing season months of May through September. It's worth noting that October is, on average, warmer at Tablas Creek than it is in Avignon, by an average of 3.6°F. That was surprising to me until I remembered two things. First, we are a lot further south than Avignon, which is at the same latitude as Eugene, Oregon. That means that October, when we've passed the fall equinox, the days get shorter faster in the south of France than they do here in California. Second, October is the rainiest month of the year in Chateauneuf-du-Pape, while it's still usually dry and sunny here. So while October nights are still cooler in Paso Robles than Avignon (an average low of 46°F here vs. 51.2°F in Avignon) the days here are so much warmer (an average high of 83°F here vs. 71.6°F in Avignon) that the average ends up higher. So why didn't I include October in the averages above? A lot of it happens after the last grapes are picked, particularly in France, where it's rare to pick after the first week of October. Even here, we typically finish some ten days or so before the end of the month.
What does all this mean? I think it's long past time for people to reevaluate the idea that Paso Robles is a hot climate, at least compared to the Mediterranean regions of Europe. It's a sunny region, to be sure. Sometimes that translates into a lushness of fruit that people associate with hot years in Europe. But all you need to do to answer whether it's a hot region or not is to look at the harvest dates and numbers. We pick, on average, 10 days later than they do at Beaucastel, with lower sugars and higher acids. The average degree of Brix (dissolved sugars) that we picked at in the 2024 harvest, one of our warmest years ever, was 22.25°, which translates to an average alcohol level of 13%.
So, what does it mean when you see a Paso Robles wine at 16% alcohol? That the winery or winemaker is making a choice. Paradoxically, the cold nights (and associated high acids) here give winemakers going for a super-lush style the ability to do so while still maintaining enough freshness to keep the wine in balance. It's not our approach; we'd prefer to pick earlier and celebrate the bright acids in the finished wines. But it's a style that clearly has its adherents and its enthusiasts.
Still, don't let people blame it on the climate. Dive in and you'll see that Paso Robles is (even) cooler than you thought.