Sum of Active Temperatures (SAT)

SAT is the total heat accumulated during the growing season: the sum of daily mean temperatures ((min + max) / 2) for days when the mean exceeds +10 °C. This is a key metric for variety selection.

Grapes

Grapes are a heat-demanding crop. The ripening period of a variety determines the required SAT:

  • Very early: below 2500 °C
  • Early: 2500–2600 °C
  • Early-mid: 2600–2700 °C
  • Mid-season: 2700–2800 °C

Apples

Apple trees are hardier and require less heat. Summer varieties manage with lower SAT values, while late varieties need 2500–2600 °C.

Data: Finnish Meteorological Institute, open data.