I don't understand what's wrong with the picture. Ok, so (supposed) fire god is surrounded by snow. So what ? It makes sense that ancient Slavs, who lived largely in cold lands (cold scale -1 at least), worshipped fire gods. It shouldn't be a suprise that they saw fire (warmth!) as beneficial to homestad, cooking meals, smithing... Sun/fire makes winter go away.
By the way: there were some slavic supernatural entities associated with winter, too. There's Grandfather Frost in RUssia (spelling depends on country, Dziadek Mróz in Poland), and winter itself was commonly depicted as (not so friendly) woman.
I still intend to make a pagan slavic mod, and my implementation will have both cold -1 and focus on fire. Contradicting ? Not really. I may add some baltic (and other legeds) if I run out of ideas. The main problem seems to be finding enough information about ancient slavic military.