A picture book that I read in my childhood (early to mid 1990s) from a book that could have been written in 1960s to early 1990s. The main characters (2 to 3 sisters as I remember) fed wildlife (birds and also a few deer, there might have been squirrels as well) apples and nuts and seed in the snow outside of their house. I believe the sky was darkened as if it were night. The setting was fairly Germanic or Nordic. The house where the characters lived was either a log cabin or a Tudor style home. I believe a few of the animals looked in through a window in the house prior to getting their food. Outside the home there were a few evergreen trees. Set before Industrial Revolution.
I cannot remember for sure if this was a Christmas story or if it was only winter, but I lean towards believing the inside of the house was decked with garlands. I am pretty sure it is in English, but it could be in German as well.
The details don’t quite match, but I strongly recommend that you check out The Snowstorm by Selina Chonz (illustrated by Alois Carigiet, who won the Hans Christian Andersen Medal in 1966). It was written in 1955, in German (the author was a Swiss poet). Florina is definitely feeding birds on a snowy day in the first inside illustration. She does not have sisters, though. The story is about a near-disaster and the sled parade that follows.
See here for more details in Solved Mysteries:
http://w1.loganberrybooks.com/stumpthebookseller/?p=172