Mood, or the emotional effect that a text has, remains pretty much constant throughout this excellent reminiscence until the end, when the flashback to the narrator's childhood ends and we are thrust into the present and forced to see the impact of time on us all.
It is clear that the prevailing mood of this excellent tale is one of nostalgia - we are thrust back into an old-fashioned country Christmas from the very first paragraph:
Imagine a morning in late November. A coming of winter morning more than twenty years ago. Consider the kitchen of a spreading old house in a country town. A great black stove is its main feature; but there is also a big round tabel and a fireplace with two rocking chairs placed in front of it. Just today the fireplace commenced its seasonal roar.
Note how the details of the fireplace that has just been lit and the coming of winter create an atmosphere of Christmas with all the accompanying excitement and delight. This is a nostalgic mood that continues as we look back to how Christmas was and join in the struggle of baking and posting all of the cakes with the narrator and his friend.
However, from the one-sentence paragraph, "This is our last Christmas together", it is clear that life moves on and that time makes such poignant activity, just a "Christmas Memory" and even results in the death of Queenie:
A message saying so merely confirms a piece of news some secret vein had already received, severing from me an irreplaceable part of myself, letting in loose like a kite on a broken string.
It appears that time separates us from both our past and from those that we love best. It is this shift that moves the mood from one of nostalgia to one of sadness and sombreness as we recognise the dominion that time has over us as well.