It's probably The Dark is Rising by Susan Cooper. It's the second book in the series.
The main character of the second novel, and a major character in the entire series, [Will Stanton] is the seventh son of a seventh son, in a large, close human family. His eleventh birthday marks the beginning of his magical awakening and rise to power as the last of the Old Ones. The Dark Is Rising tells how he came to power, met Merriman Lyon, and accumulated the six "signs" to help fight the Dark. Will is the last of the Old Ones; no others will be born after him.
A set of six circles quartered (divided evenly in four sections) by crosses. The six signs are each made of a different material and represent a different element: wood, bronze, iron, water, fire, and stone. The six Signs represent the Six champions of the Light, referred to in the recurring Poem of the Dark Is Rising series, as "three from the Circle, three from the Track". When used, the signs have the power to repel the Dark.
The whole book takes place in the winter, but the Dark also is tied to cold, as I recall. Likewise:
The rooks: The majority of these birds are servants of the Dark and attract their forces wherever they are seen.
There was a (loose) film adaptation in 2007 called The Seeker. There is a question here analyzing the differences.
It is a classic of YA fantasy and many people have read it (and asked about it). Below is a link to a similar question. I'm including it since it has links to other, related questions itself.