California was badly zapped last week by a deep trough of cold air that spread south from Canada and brought freezing nights from Mendocino to Santa Barbara. The perils presented by this frost were made more severe by the fact that it followed a week of unusually warm weather, where it neared 90 degrees at Tablas Creek and was well over 90 in downtown Paso Robles. Nearly the whole vineyard had sprouted, in many cases 6 inches or more.
As the frost approached last weekend, forecasts looked terrifying. On frosty nights, the weather station at Tablas Creek is typically the coldest in Paso Robles, and it is not even in the coldest spot on the property. Forecasts were suggesting that temperatures would range from 26-33 degrees in the appellation, which we usually project to temperatures as low as 23 or 24 in our coldest spots. When it's this cold, the frost prevention fans that we use aren't effective; the only way to save the new growth is with overhead sprinklers. And we don't have enough water for those.
We did indeed have three cold nights in a row. The nights of the 21st, 22nd and 23rd of April all registered lows at our weather station between 28 and 29 degrees. But, in an unusual reversal, it was colder on the east side of town than out at Tablas Creek. And, Paso Robles seems to have been less heavily hit than other regions; Napa, Sonoma and the Sierra Foothills all report significant damage, and even vintners I've spoken to in Santa Ynez see more damage than we do.
In driving around the vineyard this afternoon with my dad, we'd estimate maybe 5% of new growth has been damaged by this frost. A typical section is below, with some vines at the very bottom of a swale showing browning, but the vast majority of the vineyard looking fine:
As always, the frost damage is curiously selective, with damaged shoots just inches away from others that are fine. Still, given how scary things looked a week ago, we're counting ourselves very lucky.
We hope that we're largely out of the danger zone now; it hit 90 degrees here both days this weekend. And we always figure that once we get into May we're pretty much safe. And we're ready for a break. We ran our frost fans seventeen nights this spring, nearly double our annual average.