[Bonfire]

You're definitely not going to get seasonal temperature shifts in all your provinces. Opening up some of my test games I'm only seeing a temperature shift from seasonal variation in something like 1/3 to 1/2 of provinces under dominion in early, mid, and late winter.

Assuming the ceiling eliminates 5% income penalty in 1/2 provinces 1/4 of the year. 5% / 8 = 0.625%
This means H3 or C3 is about 4.375% income hit over H2 or C2. So the ceiling helps but I don't think it helps as much as people think. However going H0 to H1 changes one of the seasonal shifts from a loss to a gain giving you an extra 2x0.625% or 1.25% from what it takes away so H0 to H1 is about a 3.75% income hit whereas H1 to H2 is just a straight up 5% hit. This means H3 is about a 13.125% income hit total. At least assuming I got that math right.

The main reasons you might want to take a temp scale closer to your ideal over order would be if you also had heavy luck scales and wanted more random events or wanted to avoid the encumbrance penalty from severe heat.

As for Yomi I would always take at least H1 if only to protect the Hannyas from the cold blooded penalty.