Month | 2011 y-2012 y | 2012 y-2013 y | 2013 y-2014 y | |||
average temperature | negative accumulated temperature | average temperature | negative accumulated temperature | average temperature | negative accumulated temperature | |
11 | 6.4 | −0.1 | 4.1 | −3.0 | 6.4 | −1.9 |
12 | −1.3 | −63.7 | −4.1 | −127.5 | 0.7 | −31.3 |
1 | −3.5 | −137.2 | −3.9 | −120.9 | 0.4 | −20.3 |
2 | −1.4 | −28.3 | −0.6 | −41.0 | 0.2 | −33.4 |
3 | 5.8 | − | 6.5 | − | 10.3 | − |
4 | 15.7 | − | 12.8 | − | 17.4 | − |
Average | 3.6 | −57.3 | 2.5 | −73.1 | 5.9 | −21.7 |
Overwintering rate (%) | 75.2 | 38.9 | 93.4 |