Grapes and Health — Online Module (Week 1): Session Distribution Impact of agronomic practices and industrial processing on the stability of the bioactives in grapes

Grapevines thrive best in warm, dry summers and cool winters. The mean maximum temperature of the warmest month should be above 18-20°C, and above freezing in the coldest month. High humidity can increase disease and pest risk, while rain or cloudy conditions during blooming can lead to poor fruit set.
Temperature is the most critical factor for grapevine growth. Grapevines thrive when average daily temperatures during the growing season range between 25°C and 32°C (77–90°F), which supports optimal photosynthesis, sugar accumulation, and acid balance in the berries. Extreme heat above 35°C can reduce photosynthesis, thicken berry skins, and negatively affect fruit quality, while cool climates may slow ripening and result in higher acidity