In my hometown just south of the Frozen Tundra, Autumn made its presence known last week. I'm
Reflect the Mood or Theme
A classic use of seasonal change is as a mirror to the book's plot or theme. Got love, laughter and lighter topics? Spring and summer are perfect settings. Cue autumn leaves and winds when dramatic turning points emerge, and get ready for events to turn bleak and desperate for the characters once "Winter is coming." (I couldn't resist.)
Incite (or Delay) Action
Hand-in-hand with the thematic expression of seasons is a more practical side. What does the change in weather mean for the reality of your book's action. Heavy snows or hard summer rains can delay battles or close roads, while autumn often means harvest time and festivals. Whatever the change of season means in your book, make the most of it. Use it to push the characters into action. What options don't they have in this new season that they did before? What new options emerge?
Limit (or Expand) Geographic Scope
Just like cold and weary troops have to fight differently in the winter, your characters have to think differently about how they'll travel and what they can access in each season. Do falling leaves obscure a much-needed path? Does a frozen pass or swollen river mean your MC can't cross for days or weeks? Or, maybe she CAN cross the ice to a region that's never been accessible before. That happened with Apostle Island sea caves on Lake Superior last winter because of the record cold.
Mix Things Up with Fresh Descriptions
Seasonal change doesn't have to bring huge variations in your book. It's fun to play with the little things, too. How is the clothing different, the food, the customs? The list goes on. Get with the season and enjoy it!