Cold:
* The air was as cold as a witch's kiss.
* The wind howled like a wolf in the frozen night.
* The snow was so cold it felt like needles pricking my skin.
* The frozen lake was as still as a sleeping giant.
Snow:
* The snow fell as softly as feathers.
* The snowdrifts were as high as mountains.
* The snow glittered like a million tiny diamonds.
* The snowflakes danced like ballerinas in the wind.
Other:
* The winter sky was as grey as a storm cloud.
* The trees were as bare as a freshly-painted wall.
* The winter sun was as weak as a fading candle.
* The fireplace crackled like a hungry dragon.
These are just a few examples. You can get creative and use your imagination to come up with even more unique and evocative similes for winter!