Prosser, Wash. -- Temperatures in the Horse Heaven Hills this morning were climbing toward 78°F as Rick Hamman, director of viticulture at Hogue Ranches in Prosser stood in amid Merlot vines at the Zephyr Ridge vineyard. A cool spring has retarded development in many Northwest vineyards, and Hogue’s are no exception.

“We’re experiencing not only quite a delayed bloom -- it’s looking like it’s at least two to three weeks behind -- we’re also getting an uneven pattern,” Hamman said. “You’ve got some vines that have pea-sized berries right now and still blooming.”

While vines have a tendency to respond well to improvements in weather conditions and catch up, Hamman foresees harvest being delayed about two weeks if the cool weather continues. Temperatures through the July 4 weekend aren’t expected to rise above 80°F, and Hamman is mulling the prospect of smaller, looser clusters requiring closer management.

“It looks like we may have to adjust some crop levels to accommodate a later harvest,” he said.

The situation is similar across the Northwest. Tweets on social media sites and chatter among winemakers have many expecting a cool year with lower yields, contributing either to some solid cool-climate white wines or reduced yields to keep inventories in line with still-sluggish consumer demand. On the other hand, cool weather stands to keep acidity in balance, something that appeals to Brandon Moss, assistant winemaker at 500-case Gramercy Cellars south of Walla Walla. “We don’t add acid to any of our wines, so I’m picking to preserve acidity,” he said. “I generally want a little later ripening; so for me it’s looking like as long as we have a warm summer, it’s no problem. We’ll catch up.”

Gramercy’s low-lying 4-acre estate vineyard near the Oregon border has received abundant moisture that’s stimulated more vegetative growth than anything else. Walking through its blocks of Tempranillo, Syrah and Cabernet Sauvignon, Moss saw some spots that are through bloom and others that still awaiting pollination.

“The canopy’s really built up, but the clusters are probably not as far along as they normally are at this time of year,” he said. “That’s probably going to be the main thing early on in the season: Trying to control the amount of leaves and shoots that are coming up and making sure that energy is diverted to the clusters.”

Good growth is also evident at 20,000-case Lange Estate Winery and Vineyards in Dundee, Ore., where general manager and winemaker Jesse Lange said the wet spring turned around last week and warmed up significantly.

“It was a pretty brutal spring, but everything’s just cranking along in the vineyard right now, and we’re trying to keep on top of it,” he said, noting that today’s weather is sunny and 74°F. “We’re probably about 5% through bloom right now. It’s not hot enough to bake anything. This is perfect growing weather.”

While crop progress may be 10 days behind at his 45-acre vineyard of Pinot Noir, Pinot Gris and Chardonnay vines, he noted that every growing season is different, and he’s not about to worry. “It’s not a year where I’m freaking out at all,” he said. “There’s plenty of growing season to fret about, being a farmer. I don’t want to start early.”