Temperatures: Diurnal Temperature Range

The difference between the daily high (maximum) and low (minimum) temperatures is called the diurnal temperature range, commonly referred to as DTR.

Four factors mainly determine the typical temperature (the measure of the kinetic energy of air) of an area:

• Latitude: higher latitudes have lower temperatures due to less direct solar radiation
• Land and Water: areas near water have more stable temperatures and fewer shifts in temperatures throughout the day and seasons
• Ocean Currents: warm ocean currents can bring heat to coastal areas, and cold currents can take heat away from coastal areas.
• Elevation: Areas with high elevations tend to have lower temperatures due to less air pressure.

Less variability in the temperatures in the time leading up to harvest can improve the quality of the grapes. However, some grapes ripen better in areas with large DTRs, while others do better with smaller DTRs.