Winter and spring frosts: Severe winter frosts and spring frosts, which can occur as early as bud-break in April, are particularly dreaded. Temperatures below -2°C can freeze young buds, reducing future harvests.
Rainy and cool periods in summer: Although moderate summer temperatures are beneficial, prolonged periods of high heat (over 35-40°C) can slow or block photosynthetic activity, damaging young berries and disrupting tannin synthesis.
Severe thunderstorms and hail: Severe summer thunderstorms can cause considerable damage, especially hail, which can destroy bunches of grapes.