Why we're glad for the wet 2023-24 winter and glorying in the (so far) cool 2024 spring

This past weekend was Memorial Day, and we spent Saturday evening with friends on their patio. I wore jeans and a long-sleeve shirt and brought a quilted Tablas Creek pullover for after the sun went down. It turned out I needed it starting around 6pm, and the friends broke out their collection of blankets to keep us warm while we hung out and chatted as the light faded and the stars came out. It was lovely. But it was also weird. This is late May! Where was the heat?

We usually assume that Paso Robles Wine Festival, always the third weekend in May, is going to provide the first summer weather of the year. Our goal was always to get a prime table under a big spreading oak tree so we had shelter from the 90° heat. Not this year. The day was sunny but breezy and cool, and as the afternoon drew to a close and the wind started whipping, we were looking for patches of sun to warm our backs. I'm not complaining; I would always prefer conditions like this to it being sweltering for a wine festival. But take a close look at the fleece and denim among our pouring crew:

Team Tablas at 2024 Paso Robles Wine Festival

Those are just two anecdotal examples, but looking at the weather since the beginning of April bears out that it's been cooler than normal. The average high has been about 4°F cooler than normal, and the average nighttime low about 3°F cooler than normal. That may not seem like much. But six days haven't made it out of the 50s. Another 13 days haven't made it out of the 60s. And we have yet to hit 90°F even once. 

April and May 2024 Temperatures vs Average

Looking at it a different way, the first two months of the 2024 growing season have seen high temperatures been slightly cooler than the same stretch last year, which was by far our coolest year in more than a decade. The net result is that we're just starting flowering at a time of year when in a more typical year (like 2021) we'd have been at its peak.

This slow progression is consistent with the winter that we saw. Now that we're likely past any more rain, we can compare the winter of 2023-24 with normal. First, total rainfall compared to previous years, where you'll notice that it was above average at more than 29 inches, but nothing close to the crazy rainfall we got last winter:

Rainfall by year 1996-2024

Looking by month, you'll see that we got pretty close to our average rainfall most months, with the exception of a somewhat dry beginning to the winter (which we're thankful for given the lateness of the 2023 harvest) and a February that produced roughly double normal rainfall:

Rainfall by month winter 2023-24

The rain also came more gently than we often see in winters here, where most of the rain comes in a few big storms. We had 49 days with measurable rainfall, which means that we averaged only 0.59" of rain each rainy day. By contrast, in the winter of 2022-23, we had somewhat more rainy days (62) and those days averaged 0.8" of accumulation. They were also more concentrated in January and March, which were the months where we saw flooding.

While it's generally a solid rule that in California, there's no such thing as too much rain, we were just fine with this most recent winter. It takes about 15" of rain to saturate our calcareous soils and provide sufficient water for our dry-farmed vines to make it through the growing season. It takes another 10" of rain to refill our wells to capacity and start to refill the reservoirs. Anything beyond that flows off and becomes extra capacity. If the state is in a drought, extra water helps replenish critically low reservoir levels. But given that the ample rainfall last winter already did that, we didn't need another 40" year, and we were grateful not to have to deal with creeks jumping their banks or customers dealing with washouts or closures.

The moisture did help keep our soil temperatures low and delayed budbreak to a normal time. Since then, the cool weather has mostly meant that we're having to keep mowing since the grasses between the rows keep growing and with the new growth in the vines it's too late in the year for the sheep to help. That means we're living with a shaggier-than-normal vineyard profile:

Shaggy vineyard May 2024
In the mornings, we're seeing weather that wouldn't be surprising in a place like Santa Barbara or San Diego (where they have terms for this: "May grey" and "June gloom"). But in Paso Robles, what is normally a once- or twice-a-month phenomenon has been pretty regular. I took a few photos on my way into work last week in our Scruffy Hill block that will give you a sense. The atmosphere is lovely for photos, and it's relatively rare here:

Scruffy Hill on foggy morning
A close-up of one of the vines, with others marching away down the hill in the fog, is one of my favorite recent vineyard photos:

Scruffy Hill vine on foggy morning

Finally, in the afternoons we've been getting another pretty but usually rare phenomenon: a fog bank massing over the Santa Lucia Mountains to our west. That fog has burned off during the day, but you can see it looming there, ready to roll back in when the sun goes down:

Fog bank over Santa Lucia Mountains

We're not worried about any of this. The vineyard looks amazing and the lack of stress is a great thing for vine health. The wet winter and cool spring mean that you can reach into the soil anywhere and just an inch or two down you get to damp, dark earth. Plus, it always warms up in Paso Robles, and even in a cool year like 2023, we have a long enough growing season to get the grapes ripe. It looks like we might not have long to wait; the forecast for the next couple of weeks looks like we'll be getting into the 80s pretty regularly, with some low-90s possible Thursday and Friday. Meanwhile we'll enjoy the unusual scenery and glory in the lovely daytime weather. If you're visiting in the coming weeks, you're in for a treat.

Budbreak 2024: Right on Time

This winter has continued to follow a pattern something close to the platonic ideal of a Paso Robles winter. Some November rain to get the cover crop started. A cold December, to force the vines into dormancy. Regular and plentiful rain January through March, to keep soil temperatures down, but with sunny and warmer intervals, to encourage cover crop growth. And then a turn in April toward spring-like weather. And as we'd expect, as we passed the spring equinox we've started to see budbreak in our early-sprouting varieties. Below are Viognier (left) and Syrah (right):

Budbreak 2024 - Viognier Budbreak 2024 - Syrah

The rainfall-by-month graph for the winter so far shows the classic nature of what we've seen:

2023-24 Winter Rainfall through March

Budbreak, as you probably guessed from the name, is the period when the grapevine buds swell and burst into leaf.  It is the first marker in the growing cycle, a point when we can compare the current season to past years.  Upcoming markers will include flowering, veraison, first harvest, and last harvest.  And like harvest, budbreak doesn't happen for every grape simultaneously. Early grapes like Viognier, Grenache Blanc, Grenache, Vermentino, Cinsaut, and Syrah tend to go first, followed by Marsanne, Tannat, and Picpoul, and finally, often three weeks or more after the earliest grapes sprouted, Roussanne, Counoise, and Mourvedre. We've seen budbreak in all the early varieties, but are still waiting even for the middle varieties like Marsanne, which I was surprised to find still fully dormant on a ramble around the vineyard yesterday:

Budbreak 2024 - Marsanne

This year is about average for us, significantly later than most of our drought years, though a couple of weeks earlier than 2023. The timing that we're seeing comes despite that we haven't recorded a below-freezing night here at our weather station since February 12th. That budbreak waited some six weeks after our last frost reinforces the importance of wet soils, which hold cool temperatures better than dry soils do. For an overview, here's when we saw budbreak the last dozen years:

2023: First week of April
2022 Mid-March
2021: Last week of March
2020: Last week of March
2019: Second half of March
2018: Second half of March
2017: Mid-March
2016: Very end of February
2015: Second week of March
2014: Mid-March
2013: First week of April
2012: Mid-April

In addition to the variation by variety, there's variation by elevation and vineyard block. Grenache is a good example. I took the following four photos as I walked up the hill. The first photo is from the bottom of the block, where cool air settles at night. You can see the buds swelling, but no leaves yet:

Budbreak 2024 - Grenache bottom of hill

A little further up the hill, you see the first leaves emerging:

Budbreak 2024 - Grenache lower middle of hill

At roughly two-thirds of the way up the hill, you see some buds unfurling larger leaves:

Budbreak 2024 - Grenache upper middle of hill

And at the top of the hill, nearly all the buds are out:

Budbreak 2024 - Grenache top of hill

It will be another few weeks before we see much sprouting in late-emerging grapes like. This is Roussanne (left) and Mourvedre (right), both looking more or less as they would have in mid-winter:

Budbreak 2024 - Roussanne

Budbreak 2024 - Mourvedre

Now our worries turn to frost. Before budbreak, the vines are safely dormant, and a freeze doesn't harm them. But once they sprout, the new growth is susceptible to frost damage. April frosts cost us roughly 40% of our production in both 2009 and 2011 and a May frost cost us 20% of our production in 2022, with Mother's Day marking the unofficial end of frost season. So, we've still got more than a month to go before we can relax, and I'm thankful that it will be a few weeks before our later-sprouting varieties and our lower-lying (read: more frost-prone) areas are out enough to be at risk. 

That said, there's nothing particularly scary in our long-term forecast. We're supposed to get one more late-winter storm later this week, but it doesn't seem likely to drop below freezing. After that, we're expecting drier weather as the storm track shifts north. But there's a long way to go.

Meanwhile, we'll enjoy the rapid changes in the vineyard, and the hope that always comes with the emergence of new buds. Please join me in welcoming the 2024 vintage.