With vintage kicking off across Europe, growers are looking anxiously at the skies in case Mother Nature has any more nasty surprises in store.

Bad weather has affected France, Italy, Portugal and Germany during the growing season, but a recent run of warm, sunny weather has growers cautiously optimistic.

In Germany's Rheinhessen, picking of the earlier-maturing varieties such as Solaris began on August 8, 20 days earlier than last year. Ernst Buscher of the German Wine Institute (DWI) in Mainz said the early ripening was a silver lining to a season that "had no real summer".

Growers were picking in Pfalz and Baden as well, with predictions of a good harvest if the sun comes out.

In Spain, the early varieties are already being picked and the forecast is for a good-quality harvest of normal proportions. Priorat's Toni Alcover said production this year would be 10 percent higher than in 2013, with quality looking promising.

"The humidity recorded so far this summer and the contrast between day and night temperatures will result in more aromatic wines," he said. "Everything depends on the expression vintners want to give their wines."

In Penedes, growers have already started picking Chardonnay and Pinot Noir, while indigenous Cava varieties like Xarel-lo will commence next week. Jane Ventura of Bodegas Augustus was expecting a high-quality crop because of the slow maturation period.

Forecasts from Castilla-La Mancha, Valdepenas and Catalunya were also positive.

The Portuguese summer has also had issues, with the Douro enduring wet weather and mildew. It was an unusual year for the region, with some areas picking earlier than last year and others yet to start.

Carlos Pereira, head of viticulture at the Regional Directorate for Agriculture and Fisheries of the North (DRAPN), said the "vineyards in the Douro this year have been a little hectic."

Winemaker Gabriela Canossa, from Quinta Maria Izabel, said vineyards had been treated for mildew and she was now just waiting for the grapes to ripen. "The next 15 days will dictate everything," she said.

However, the rain had its advantages for the dryer areas of the Douro, which won't suffer so much water stress. According to Pereira, that may translate into a great harvest.

Vinho Verde producers are still waiting to see how the harvest will go, with late rain causing worries about disease.

Grower John Garrido said it was too early to tell what effect the rain and cooler weather would have.

"The lack of heat may delay development of the grapes, but it can be offset if now we get some hot days. Then we will be picking at the normal time and looking at a good-quality grape harvest," he said.

Several important regions on both sides of the Alps in Italy and France were plagued with cool and very rainy weather in July, delaying harvest and causing concerns about quality.