Combine sugar and water in a small pan and bring to a simmer over medium heat, stirring until sugar dissolves. Remove from heat and let cool for 10 minutes. Place the cranberries in a bowl and pour the syrup over the top. Let cool completely, cover with plastic wrap, and refrigerate overnight.
Drain cranberries in a colander over a bowl, reserving the syrup for another use. Place sanding sugar in a shallow dish. Add the cranberries in batches, rolling to coat with sugar. Spread sugared cranberries in a single layer on a baking sheet; let stand at room temperature until dry, about 1 hour.