Bear with me:
Eastern Reach is the southern hemisphere of Eora (http://pillarsofeternity.gamepedia.com/Eora#Eastern_Reach)
The climate is temperate there as you can see for yourself playing Pillars of Eternity 1
It means that further south would make the climate change to colder regions, and White That Wends proves it (http://pillarsofeternity.gamepedia.com/Eora#The_White_that_Wends)
In a PCGamesN article Josh Sawyer states “If you’ve gotten tired of seeing temperate forests and meadows for 80 hours,” Josh Sawyer tells us, “Let’s take a look at something else.” (http://www.pcgamesn.com/pillars-of-eternity-2/pillars-of-eternity-2-release-date-story-setting)
So the Deadfire is clearly a warmer setting than Eastern Reach, as you can see in he FIG campaing
But we know that it is much further south from it (http://pillarsofeternity.gamepedia.com/Deadfire_Archipelago)
Thus the Deadfire should either be colder, or located to the north
OR the ER shoulda been in the northern hepisphere, but that would make no sense with the Ixamitl savannas!
Double-u tee eff, mate?