A welcome, gentle start to the Paso Robles rainy season

What a difference a year makes. This week last year we were in the middle of a three-week stretch where four separate atmospheric river storms slammed into the California Central Coast, totaling nearly 20 inches of rain. That was more than we'd received any of the three previous winters, and all that water overwhelmed the creeks, culverts, and drainage basins and produced flooding with visual images so dramatic that we found ourselves the subject of stories in Decanter, Wine Spectator, Fox Weather, the San Francisco Chronicle, and even the BBC.

Still, while last year was extreme, it's usually wet in December. This year's monthly total was 5.13", or 103% of normal for what is typically our second-wettest month. Even better, it's come gently, in three separate storms, each of which spread out across two days. After a November where we received about 80% of our expected precipitation, this year is trending curiously... normally. It's also been relatively warm; after eight below-freezing nights in later November and early December, we haven't frosted since December 13th. These last three warm, wet weeks have provided outstanding conditions for the cover crop to get established, and it's ahead of last year's growth even though we've only seen average (instead of well-above-average) rain:

It appears that January is continuing with more of the same pattern. Last night brought another half-inch of rain, and there are two more small storms in the 10-day forecast, though nothing that looks like it's going to really dump on us. As long as we get these periodic smaller storms, that's just fine. We do need it to stay wet in January (typically our wettest month of the year, at an average of 5.81" of rain) because it accounts for nearly a quarter of our annual total. Our core rainy season is just four months, with December through March accounting for 78% of our total rainfall since we installed our weather station in 1996. If we don't get our moisture then, it's hard to make it up later.

We are a long way from worrying about oversaturation; there's no water flowing yet in Las Tablas Creek, and while the larger creeks and rivers have had a little water in them in the immediate aftermath of the storms, they're a long way from the steady flows that we saw well into spring in 2023. That said, the soils are deep brown and wet down through the root zones of both grapevines and cover crop. And water-loving plants (and fungi) are having a field day:

A priority for us at this time of year is doing everything we can to encourage the absorption of the rain that falls and discourage runoff. One of the techniques that we use is keyline plowing. This ancient technique prescribes digging deep furrows in alternate rows of our dry-farmed blocks, keeping roughly perpendicular to the slope. These furrows slow the downhill flow of water and encourage absorption instead of runoff. What's more, because these furrows cut through the layers but don't turn the soil over, the disruption that they provide to the soil networks is minimal. A photo of our Scruffy Hill block is a great example:

So if the soils are so nice and wet, why are we hoping for regarding additional rain? Well, there are two reasons. First, the calcareous soils here in west Paso Robles have a tremendous capacity to absorb, store, and transport water to deeper layers. Additional rain will help recharge the underground rivers and lakes (and everyone's wells). Second, wet soils have a greater capacity to stay cool compared to drier soils, and rising soil temperatures is one of the most important factors in determining the date of bud break. Rain well into March last year helped keep our vines dormant longer than we've seen in any of our drier seasons, and every week that the vines stay dormant through March and April measurably reduces our risk from spring frosts.

But that's a worry for the future. For now, we'll glory in the lovely green growth we're seeing everywhere, the blue skies overhead during this period between storm systems, and feel great about a season that has so far felt benign. After all the excitement of the last two years, we'd be happy with a little bit of boring.