[Bananadine]

The manual claims that temperature also affects the likelihood that burning or freezing units (where "freezing" is the state that turns a unit blue-white, I think) will stop burning or freezing in a given round.

And the difference between ice elementals and water elementals is occasionally very important.

None of that has anything to do with a nation's preferred climate though. And mechanically, the Caelian ice armor, and Strength of the Spring, and everything else I can think of that has to do with weather, is independent of a nation's climate preference. Illwinter probably wouldn't add an Abysian unit that uses ice armor, but a modder could, and I guess the game wouldn't complain. Is it really true, then, that the only direct effect of the nation's preference is on supplies and taxes?