Diurnal Range
/dy-UR-nul RAYNJ/The difference between day and night temperatures.
Full Definition
Diurnal range (or diurnal shift) is the temperature difference between daytime highs and nighttime lows. Large diurnal ranges (common in high altitude or continental climates) help grapes develop flavor complexity while retaining acidity, as cool nights slow respiration and preserve acids. Regions like Mendoza and Walla Walla are noted for this.