Veraison is a fancy French word that says the ripening process has begun. The cultivars with purple pigments start to develop color. The unpigmented (green) varieties start to soften and become less green.
As the seeds mature and start becoming capable of growing, the vine makes the fruit attractive. It becomes sweeter, less bitter, more colorful, and aromatic. All to attract animals (like us, and birds) to eat the fruit and hopefully move seeds to a new location.
In reality, it’s about birds. They eat a berry and a few hours later poop out the seeds in a fertilizer packet.
In the natural scheme, grapevines use trees to get up to the sun. Birds sit and poop in trees. Seeds are deposited at the bottom of trees. Brilliantly showing the power of Natural Selection.
From our standpoint, veraison means time to put up bird netting so we harvest the fruit instead of the birds. It tells us nothing about the harvest time. The weather the 30 days before harvest is what really counts.
A purple berry in Zinfandel tells us nothing. We may harvest Zinfandel in mid-October or early November. The weather today doesn’t matter much. Earlier than average veraison can still end up as a later than average harvest time and vice versa.
Veraison is just the first obvious change, the first photogenic change. It is, for some illogical reason, kind of exciting. In reality, it tells us nothing. Hope is what keeps farmers going, so maybe it’s something rather than nothing?