Diurnal Shifts

If you’ve ever been to wineries in Napa Valley (or most regions of California), you know that they love talking about “diurnal shifts”. A diurnal shift is defined as “dramatic temperature differences between daytime highs, and nighttime lows”.

In Maryland, we seldomly talk about diurnal shifts because we rarely get them to notable extremes. However, the past two weeks have proven otherwise; so let’s talk about it.

The days have been sunny and warm. The nights have been cool and clear. We’ve been consistently getting 25-30 degree temperature swings. This is what Napa sees regularly.

The sunny days encourage sugar and flavor development, while the cool nights help preserve acidity, aromatics and freshness. Dry weather increases flavor concentration.

Chardonnay was picked on September 1, giving us some of the best quality acids we’ve ever brought in. Albariño is next, but still has time. It may be the latest Albariño pick on record. Which we think should be a good thing. Time will tell.

For reds, we expect these cool nights to slow things down, allowing flavors to evolve, and complexity to build. Up to a certain point, more hang time on the vine is usually a good thing.

All of this sounds almost too good to be true. We know that rain is coming, but question is when, and how much. That’s the “x” factor.