Holiday Book Promotion During the Off-Season

Do you have a holiday book and wonder how to market and promote it other times of the year? If it's a Christmas book, declare Christmas in July. Put together a contest/drawing and fill a basket full of Christmas and current holiday goodies.

Do leprechauns celebrate Christmas? Have a combo St. Patrick's Day/Christmas prize basket.
Snow in the Summer?
It doesn't seem like the most wintery/Christmasy time of year. You could make a combo basket/bag full of Fourth of July paraphenelia, sunscreen, lotion, suntan oill. Santa has delicate skin. Try to name the gift basket/bag as Santa's summer essentials. You can tuck Chrismas paraphenelia in it, too. Instead of a bag, buy an old timey suitcase cheap. You could promote it with the phrase "Win Santa's Suitcase".