Galebound takes place on a tidally-locked planet, loosely based on Gliese 581g. It orbits a red dwarf, resulting in a reddish sky that is further reddened by the fact that everyone lives in the terminator, where the sun is permanently trapped in dusk. Thus, that area -- and eventually the planet as a whole -- got called Dusk. The world has no seasons and basically no day-night cycle, so it's almost like time never passes.
However, there's another, much larger planet in the star system between them and their star which periodically causes an eclipse. The eclipse happens every twenty-seven hours and lasts for one hour, which forms the basis of their time-keeping. Clocks are set with "midnight" being the start of the Dark Hour.
Because the world is tidally locked, half of the world is covered in ice and the other half is scorched barren. In the center of that scorched land is the eye of a tremendous windstorm--the titular Gale.
As for the "local" setting, it takes place mainly in two rival provinces: Evenheim and Cymaria, separated by the sea. At the heart of each province is the eponymous city-state and seat of government. Both are ruled by guilds (basically an aristocracy), but Cymaria still hangs on to its monarchy as a figurehead. It's equivalent to our world's 1820-30's with some French flavor.