Simulated frost stress index as a function of both frost resistance (−13 °C, −18 °C and −23 °C) levels and acclimation rates (35, 42 and 49 days) for 2011–2012 and 2015–2016 winters. The computation is conducted for Dijon place. The winter T_min and T_max showed contrasted fluctuations during January and February 2012 with an intense cold period of three consecutive weeks (observed minimal T_min of −15.7 °C the 5^th of February) subsequent to a relative long warm period. Winter 2015–2016 experimented a minimal T_min of −9 °C the 24^th of November 2015 with less fluctuations than winter 2011–2012. Note that the date of sowing is fixed the 25^th of October.