Since when does Paso Robles get "May grey" and "June gloom"? Welcome to 2023.
June 05, 2023
If you live in California, you're not going to be surprised by this update. But it's been chilly so far this year. Sure, the winter made headlines, with record-breaking rains and cold temperatures. But even since then it hasn't exactly felt like sunny California. After a more-or-less normal April, we've gone back to a weather pattern in much of May and June that feels more like March -- or Mendocino -- than midsummer. Today we've had a heavy overcast as an unusual late-season low pressure system drifts over our area. This is not a sky that you expect to see in conjunction with this landscape:
It's not just the lack of sun. Since May 1st, temperatures here averaged nearly 7°F lower than normal, with only 12 days above seasonal highs and 22 below:
The cool patterns looks likely to persist through at least the middle of the month and perhaps longer, as it's caused by some longer-term conditions (static high pressure systems over the sub-arctic and low-pressure over the sub-tropics off the coast of California). For a more in-depth explanation, I recommend Daniel Swain's Weather West blog and Twitter feed:
New Weather West post out today: Unusual June pattern this week with some showers and thunderstorms possible in unusual places (though fire concerns are low); more cool weather could continue through much of June.#CAwx #CAwater #CAfre https://t.co/cKy6wsb9Ak
— Daniel Swain (@Weather_West) June 5, 2023
The last six weeks or so have been characterized by a deep marine layer and on-shore flow, which has meant that even our warmer days have usually started out foggy. That's not unusual in the early spring here, but it's typically not the case even by early May. And having deep gray clouds over lush green grapevines in early June is even more unusual:
The net result has been that the growing season, which got off to a slow start before catching up a bit in mid-May, has fallen further behind again. We're now something like a couple of weeks behind average, and more like three or four weeks behind most recent years. For a good comparison, check out the blog I published June 3rd, 2022 about fruit set, with pea-size berries in Grenache. By contrast, Grenache is still in mid-flowering today:
Our biggest worry right now is that cool, breezy weather isn't ideal for berry fertilization, and raises the risk of shatter. But no one I talk to is particularly concerned. It hasn't been all that windy (the last month has had only one day with a top wind gust over 20mph), we've had warmer days interspersed between the chilly ones, and it hasn't rained. Even if we do get a passing shower tonight or tomorrow, it doesn't look like it will be much, or that it will stick around for long. Plus, everyone is seeing what we are: unusual vigor in the vineyards thanks to all our winter rain, with large clusters and plenty of leaf area. If we lose a small percentage of that crop, we can afford that better than we would have been able to the last few years.
Finally, there's plenty of runway left in the growing season. We've gotten used to starting to pick in August and finishing by mid-October. But in the 2000s it was more normal that we'd start in mid-September and finish in early November. In Paso Robles that's not a huge risk, since the rainy season doesn't usually start in earnest until around Thanksgiving. That's a big part of why we chose this location. So if we need to wait, we wait. There are even benefits to doing so, as the grapes will spend longer on the vines and we're more likely to be picking in cooler weather.
Meanwhile, we'll enjoy the unusual backdrop to our vineyard activities. "May grey" and "June gloom" aren't normal features of Paso Robles weather. But it seems like in 2023 we're getting a taste of both.