I forgot to reply about the Fluctuations of Temperature.

The scales of your Dominion are semi at the whim of the game. For no understandable reason they will fluxuate in temperature, order, production, growth, luck and magic (more than likely all of them including turmoil etc, but these are the only ones I really pay attention to).

This is for all nations/themes. The only real exception to this rule seems to be when you choose Heart of Winter/Desert Sun, which holds fairly true to its cold/heat pushing effects.

Pushing your Cold to 3, could potentially set your scales to your preference, or sometimes not, it really depends on whatever game variable is messing with your scales. There are however sites, that provide scale adjustments that can tweak with them so there is no real guarentee that they will stay where they are supposed to.

But the main instance for choosing Cold 2 over 3, is the fact that (most of the time) your capital will remain in your Dominion temperature. Your capital, like your initial castle, has alot to do with the direction you go in the game and having a stable and consistant -5% income loss (0r -3% if you take growth 1) in the only real guarenteed large province you can in a game is a very real factor.

Starting position plays alot into the game and the speed with which you expand, research and a variety of things. So if you found/find that Cold 3 works to your benefit more than your hamperment, I would take it. I personally don't like to count on assurances of randomness (like the fluxuating scale(s)).