The warm, sunny weather of last week seems like a distant memory. In the last 24 hours we've had two hailstorms (the second with peals of thunder), a hard freeze, with temperatures down as low as 24 degrees in our coldest spots and even the tops of the hills below freezing, and about an inch of snow.
April is often an erratic weather month. It can be warm and summery. It can be cold and rainy. And it's the month where we worry most about frost damage, as most years it's been warm enough by then for the vines to sprout. We're comparatively lucky that this year March was cool and wet, and bud break perhaps three weeks behind normal. This later start to the growing season meant that most of the vineyard was still dormant last night and should have escaped the bulk of the frost damage.
A few photos will give you a sense of how unusual this weather was, for spring. First, a photo of a vineyard block in which we've mowed every-other row. We mow to allow cold air to drain off the hillsides and away into the valleys, protecting the hillside vines from frost damage. In today's snow, the mowed rows showed white while the unmowed rows were still green:
The hail was equally impressive, lasting long enough to cover exposed surfaces. Our patio tables looked like they'd been covered with a white blanket:
As impressive visually as the snow and hail were, it's the cold that we worry about. And it is cold. Last night at 11pm our weather station was reading 32 degrees. At its coldest it got down to 28 degrees in the middle of the vineyard, and 24 degrees in our coldest pocket down near the creek. Even today it's been cold. Winemaker Ryan Hebert came inside to report that the frost protection fan that is set to automatically turn on at 34 degrees had come on unexpectedly at 1pm. That's unprecedented.
We frost protect our vineyard principally with fans, as our water resources are limited. But the fans just promote circulation, and so don't warm up the surface air if the upper atmosphere is cold too. We do protect about 20 acres with water, which works more reliably in colder temperatures. Due to the buffering capabilities of water, as long as there is running water, the vines can be encased in ice but not get below 32 degrees. On a frosty morning, the icicles can be impressive:
Paradoxically, it appears that it's our chilly location that may have helped us this time. As we're colder than most Paso Robles spots, our vines are still dormant, while our neighbors (almost all of whom have vines out further than ours) reported significant damage from last night's frost, even in top-of-hill spots that typically don't freeze. At Tablas Creek, Mourvedre, Roussanne, and Counoise are all still dormant. Much of Syrah has yet to bud out. Still, Grenache, Grenache Blanc and Viognier are all out, and I'm sure we'll sustain some damage. We have one more frosty night forecast for tonight, after which we'll be able to assess where we are.
If you're interested in more photos from today, you can find them in a Facebook photo album. While you're looking, please think warm thoughts for us and hope for cloud cover tonight.