Moderate climate GST range?

• A. 15-17°C
• B. 19-21°C
• C. 16.5-18.5°C
• D. 13-15°C

Answer: (C)

Growing Season Temperature (GST) is the average temperature during the grape-growing period at vine level and is a strong predictor of wine style. In a moderate climate, the GST is best represented by about 16.5–18.5°C. This range provides enough heat for steady ripening of sugars and flavor compounds while keeping acidity from dropping too low, helping to maintain balance and freshness in the wine. If GST falls below this window, grapes tend to stay more acidic and underdeveloped in flavor; if GST rises above it, sugars can accumulate quickly, leading to higher potential alcohol and possibly richer, softer acidity. That balanced middle range yields wines with good aroma development, structure, and drinkability, which is why it’s the correct choice.