This morning (while preparing this post for scheduling) I read an article in a news magazine summing up this past winter. The author wrote, the average temperature in Germany was +3.5°C. A winter without winterly weather. During winter 2006/2007 we even had +4.4°C on average in Germany. In Wikipedia, you can find some statistical data on the average temperature during winter even for the last centuries. So, in the period 1761 to 2017, there was an average temperature of −0,2 °C (1961–1990: 0,2 °C). But, you can also see, that there were some peaks +2,7 °C in 1795/96, +2,3 °C in 1821/22, +2,9 °C in 1833/34 or +2,5 °C in 1868/69. But there were also some negative peaks: −5,0 °C in 1939/40, -3,9 °C in 1941/42, −4,6 °C in 1946/47 or −5,5 °C in 1962/63. You see, varying of average temperatures is normal, but there are some further conditions to consider. How about the amount of rainfall (snowfall) and the physical condition: liquid water drains away quite fast while the snow keeps the soil warm and saves the roots of plants from freezing during icy nights. At the end of the winter the snow cover dews slowly and the soil is able to absorb the water much better to keep it for summer (fill up the groundwater reservoirs).
There are some advantages and many disadvantages. First, plants and animals have more time for growing their descendants (fruits and offsprings). But, vermins also have more time. And, while it is still possible to get some frosty nights ’till April/May, sprouts can grow anew, while blossoms and fruit sets usually can’t be replaced when perished by cold.