I haven't been giving out blow-by-blow accounts of this summer's weather, for two reasons. First, you probably don't care much, and anyway the impacts of mid-summer weather on the quality of that year's harvest are minor. Second, it's been remarkably unexciting (though promising) weather. We've had week after week of warm days -- typically topping out in the 80's or low 90's -- and cool nights. We've had very few cool stretches that topped out in the 70's, and until last week no truly hot stretches where the highs topped 100. OK, now you're caught up to date... at least until last week.
Last week, we got a massive heat wave, the first in three years, which sent temperatures soaring over 100 on consecutive days. The nights were warm, too, only briefly dropping below 60 before warming back up with sunrise. Then, like a driver over-correcting from a missed turn, we swung into this week, where we flirted with record low high temperatures. A fog bank loomed over our western mountains, and spread inland to an impossibly high level of 4000 feet -- the highest penetration of the marine layer I can remember in my decade here. A few of photos I took Monday should give you a sense of the drama of this fog bank, rolling in toward the vineyard:
Looking at a chart of the daily high temperatures (with the seasonal averages marked) gives you a sense of the degree to which both our hot spell and the recent cold snap are divergent from normal:
From last week, when our high temperatures were 15 degrees above the already-hot seasonal norms, this week the highs have been nearly 25 degrees below seasonal norms. Yesterday, the weather station at Tablas Creek registered a high of 64.7°. I don't have an easy way of figuring out what the record low high was out here, but the record low for July 17th at the Paso Robles airport was 71°. Even given that we're typically a few degrees cooler out here than in town, we must have been close. (The airport, if you're curious, reached a maximum reading of 73° yesterday, which is an unusually large differential with us.)
In any case, this unseasonably cool stretch, like the unseasonably warm one before, is forecast to be short-lived. We're expecting to be back in the low-90s by the end of this week, and the forecast suggests that it will continue to be seasonably warm, with seasonably cool nights, for the rest of July. And given that this range is absolutely perfect for vines to photosynthesize -- and therefore ripen their fruit -- that's just all right with us. We're still on track for a terrific vintage, maybe slightly ahead of normal in timing. Next stop: veraison.