Petite Sirah/Durif - From the Rhone. DNA testing has shown that Durif and California's Petite Sirah are the same (they are a cross between Syrah and a lesser-known Rhone grape). It can make a firm, tannic, acidic wine. Growing it in a hot, sunny climate can soften its harsher characteristics.
Petit Verdot - A Bordeaux grape that ripens easier it a hotter climate, like the Central Valley. It can be a dark, tannic grape in cooler climates.
Tannat - Another firm, tannic grape from France. It's popular in Uruguay, of all places, plus other warm areas of the world. In California it gets blended with heavier wines such as Cabernet and Syrah.
Now come some other off-the-wall varieties folks are testing now:
Fiano - A southern Italian white wine grape that may go back to the ancient Greeks.
Biancu Gentile - A white wine grape from Corsica.
Sagrantino - A very inky, tannic red wine grape from central Italy.
Marselan Noir. - A French grape that's a cross between Cabernet and Grenache. Decades ago Cab was crossed with another Rhone grape, Carignane, to create Ruby Cabernet that would grow in hot climates. It didn't do well as a variety and is mostly a bulk blending grape now.
These are grapes that don't necessarily do well in cooler climates but soften up in warm regions -- perfect for the hot Central Valley of California. Will we ever see a wine labeled as Tannat or Sagrantino from here? Probably not, they'll likely be blended with other varieties to make inexpensive red table wines. That is if they do well at all in the hot, dry Central Valley.
UC Davis, the home of California wine education, and Constellation Brands, owners of Robert Mondavi, Clos du Bois and Ravenswood among others, are cooperating on finding grapes varieties that will grow well here. Innovation is always good to see. It's usually fostered by some need. I expect this need is for more quality wine at the lower end of the price spectrum. As the recession ends and wine sales are picking up there's talk now about an upcoming shortage of grapes in the coastal regions so they are looking where land is cheaper. But don't expect to see these wines on the store shelf anytime soon. I expect this is a decade away.