More than any other season, summer seems to require rethinking one's approach to wine. While a crisp white can have an icy snap that's equally appealing in July or January, the reds of winter—brawny Cabernets, rich Zinfandels, powerful Bordeaux—feel overwhelmingly heavy when the sun is high and the weather's hot. During the summer, lightness and a refreshing simplicity trump almost any other consideration.
These characteristics may be why Pinot Grigio, to take one example, has become such a popular warm-weather wine (It has now become America's fifth-largest-selling wine in terms of volume, according to the Nielsen Company.) Like Pinot Noir, it's originally from Burgundy, though it has taken a far different path than its cousin. While the Pinot Grigio grape produces full-bodied, aromatic wines under the alias Pinot Gris in Oregon and France's Alsace region, the best-known versions are crisp, relatively simple ones from northern Italy. One good name to look for is Kris, an affordable bottling from winemaker Franz Haas.
Even if you're a diehard Pinot Grigio fan, though, keep in mind that Italy produces plenty of other great summer white wine options with more character. Floral, fragrant Falanghina from Campania is one great choice—try Mastroberardino's—as is the even more aromatic Moscato (Alois Lageder makes a good one). In the New World, Chenin Blanc was one of America's favorite wines in the late 1960s and on into the '70s. Unfortunately, its popularity helped lead to its downfall, as greedy wineries pumped up production, producing vast, flavorless crops of Chenin off industrially farmed vineyards. Now that the market for Chenin Blanc has shrunk, it's easier to find good ones, particularly aromatic, rich wines from France's Loire region (try the Chateau de Chamboureau Savennières) and lighter-bodied, often melony wines from South Africa (try Pecan Stream's bottling, or Cederberg's).
Spain has two great contributions to summer drinking: Viura, from Rioja, and Verdejo, from the Rueda region. Viura often has a refreshing green-apple tang—El Coto makes a classic example, as does Marqués de Cáceres—while Verdejo tends to have racy flavors of gooseberry and passion fruit, similar to Sauvignon Blanc. Look for Martínsancho or Naia.
Of course, there's no reason to give up red wine for months. Skip the Cabernets and Syrahs and look for lighter-bodied reds; if you can chill them to about 60 degrees, so much the better. One French red that responds well to chilling is Beaujolais. The nouveau stuff is little more than aggressively marketed grape juice. However, the region's more serious wines, labeled by the village they come from (e.g., Brouilly, Morgon and Moulin-à-Vent), are berry-driven reds light enough for fish dishes on a hot day, yet still complex and interesting. Buy the Nicole Chanrion if you can find it; otherwise Château de la Chaize and Potel-Aviron are very good options.
If you're torn between white and red, why decide? Dry rosé (not sweet "blush" wines like White Zinfandel) was created for summer drinking: It goes well with either meat or fish, and is a favorite of wine professionals on a hot day. You can buy rosés from practically every winemaking region, and made from practically any grape. If a rosé is almost as dark as a red wine, or clocks in at a hefty 15 percent alcohol, buy something else. The south of France is a classic destination for good rosé; try Mas Carlot, Mas de Gourgonnier or Domaine Begude. For a U.S. rosé, try SoloRosa or l'Uvaggio di Giacomo.