Napa Valley Wine Radio

Question fromMark (in reference to a prolonged heat wave in July of 2006): Has the unseasonably high temperatures affected the grapes?
 

Answer: Hi, Mark!  From what I’ve read and what our winemaker has said, it looks like there’s been very little effect, thank heavens.  This may be partly due to all the heavy rains last winter, which made the vines grow vigorously.  There’s plenty of leaf canopy so, if a few are sunburned, the rest have us covered (literally).

Our winemaker remarked that he’s glad he didn’t leaf-thin too aggressively, because some of the leaves got a little baked and dried out , but there aren’t enough to be an issue and the leaves provided enough shade to shelter the clusters from sunburn.

The theory is always that the hotter it is, the faster the grapes ripen but, in fact, when the temperatures get above the low-to-mid 90s the vines shut down and the heat wave could actually slow things down more than speed them up.  The vines go into the survival mode, a lot like the plants in your yard.

So, it will be interesting to see when harvest starts!  I saw the first sign of veraison (the color change) when I was out in the vineyard this morning which seems slightly late.

Hope that helps!  Thanks, Nancy