I do the same thing with our cards, but I tend to get more action shots rather than poses - sometimes the photo ends up being from the winter before, but typically nobody seems to really notice. If I get a great Christmasy/wintery shot, and it's going to be within a year, I will use it (obviously when my daughter was a baby and a toddler they were current but as kids get older, they usually don't look THAT different from one year to the next - at least my stepsons didn't). In the past, for example, I've done:
1. Stepsons in front of the tree with presents, in their pajamas on Christmas morning
2. Stepsons playing shepherds in the church Christmas play
3. Stepsons snow-tubing with dad
4. Stepsons playing in the snow during a snow storm
5. Stepsons in front of the Christmas tree and skating rink at Rockefeller Center
6. Stepsons helping chop down our Christmas tree
7. Daughter looking up the fireplace for Santa
8. Daughter riding on the cart with the Christmas tree we just chopped down
9. Daughter sledding down the hill
Maybe if you get lucky enough to get some snow, you can try for them making snow angels or posed with a snowman in front of your house.