The Wine Knows

It is blistering in the Pacific Northwest. It has been for a couple of weeks, but folks on the west side of the Cascades - particularly around Seattle and Portland - are suffering unseasonable highs well into the triple digits.

I read an article earlier today from a normally reputable source that stated Northwest growers are loving this heat. Nothing could be further from the truth.

In fact, here's the big problem: When temperatures get much above 90 degrees, grapevines "shut down." In other words, if it's too hot, the vines go into survival mode and stop ripening grapes.

Throughout June and up to about two weeks ago, conditions have been just about perfect in Washington's Columbia Valley. Highs were around 85 or 90 degrees, and every moment of sunlight was helping vines catch up from a cool spring. Now, very little development is going on because we're hitting triple digits by noon or 1 p.m. and not cooling down until sundown.

It's not like we aren't used to it; 100-plus-degree days are normal in Eastern Washington around the end of July and will last a couple of weeks. I've seen growers try different things to combat the heat. One of the most innovative (though I'm not sure how effective) is to turn on overhead irrigation to cool the air just enough that the vine keeps working.

An additional problem is sunburn, which can occur to grapes. I am less familiar with how big of a problem this can be and how long it takes to happen, but I do hear grape growers and winemakers talk about it nearly every year.

So as you swelter as you move about the Pacific Northwest, remember this: The grapes don't much care for the heat, either.